Volume VIII of the Official Records provides insight into your questions. Extracts from which follow:
VAN BUREN, ARK., March 17, 1862.
General A. SIDNEY JOHNSTON, C. S. A.:
I am at Van Buren with the army, preparing to march to Pocahontas. Will get off by the 22nd, and will reach Pocahontas by the 7th or 8th of April with 15,000 men. I will operate to assist the army on the Mississippi. It is reported that the army of the enemy have left Arkansas for Springfield. I will know positively to-morrow or next day. The country in this vicinity will no longer support an army.
Have any troops been ordered to report to me other than those called for by me from the States of Arkansas, Louisiana, and Texas?
EARL VAN DORN, Major-General.
HEADQUARTERS TRANS-MISSISSIPPI DISTRICT,
Van Buren, Ark., March 18, 1862.
General A. SIDNEY JOHNSTON:*
SIR: I have the pleasure to inform you that the entire army I marched against the enemy some days since is now in camp a few miles from this place, and that I shall march in a few days for Pocahontas, to make a junction with whatever force that may be assembled at that place. It is my intention then to fall upon the force of the enemy in the vicinity of New Madrid or Cape Girardeau and attempt to relieve General Beauregard, and, if practicable, I shall march on Saint Louis, and thus withdraw the forces now threatening this part of the State of Arkansas. The army cannot be subsisted here any longer, neither do I think that the enemy can make any serious demonstration from here until later in the....................... spring. ....................................................
General Van Dorn
Organization of the First Division, Army of the West, Major General Sterling Price commanding, March 17, 1862.*
First Brigade.
Colonel HENRY LITTLE.
17th Arkansas, Colonel Rector.
21st Arkansas, Colonel McRae.
1st Missouri.
2nd Missouri.
3rd Missouri.
Gates' cavalry.
Wade's battery.
Second Brigade.
Colonel LOUIS HEBERT.
4th Arkansas, Colonel McNair.
14th Arkansas, Colonel Mitchell.
16th Arkansas, Colonel Hill.
3rd Louisiana.
Whitfield's cavalry.
MacDonald's battery.
Third Brigade.
Brigadier General A. E. STEEN.
Missouri Infantry.+
Brooks' cavalry.
Clark's battery.
Fourth Brigade.
Brigadier General MARTIN E. GREEN.
Missouri Infantry.+
McCulloch's cavalry.
Lucas' battery.
Cavalry Brigade.
Colonel E. GREER.
Crump's cavalry.
Greer's (3rd Texas) cavalry.
McIntosh's cavalry.
Artillery Brigade.
Brigadier General D. M. FROST.
Bledsoe's battery, 4 guns.
Gaines' battery.
Good's battery, 6 guns.
Gorham's battery, 4 guns, iron.
Guibor's battery, 6 guns.
Hart's battery, 4 guns.
Kelly's battery, 5 guns, iron.
Kneisby's battery, 5 guns, iron.
Landis'' battery, 4 howitzers.
Provence's battery, 6 guns.
Teel's battery, 4 guns.
Champion's cavalry.
*As announced in Special Orders, Numbers 24, of this date, from headquarters Trans Mississippi District.
+To be organized by General Price.
Added to this force was another estimated 5000 troops [mostly new Arkansas regiments and battalions just now organizing] which joined Van Dorn as he moved eastward for his subsequent transfer across the Mississippi River. This addition of new troops prompted a revised and expanded organization.
After Van Dorn and his army had left Arkansas, General Hindman arrived to take command. Extracts from his report [also in the Official Records] show the troops that were left behind by Van Dorn as follows:
GENERAL ORDERS, HDQRS TRANS-MISSISSIPPI DISTRICT, Numbers 1. Little Rock, Ark., May 31, 1862.
Major General Hindman takes command and reports as follows:
The battle of Elkhorn was fought in March, 1862. Our forces were defeated and compelled to retreat to the Arkansas River. Soon after, in anticipation of a grand contest near Corinth, they were moved east of the Mississippi, by order of General Albert Sidney Johnston, then commanding the Western Department. They took with them from Arkansas all material of war and public property of every description. Immediately afterward Brigadier-General Pike retreated southward to the vicinity of Red River. Thus Missouri was left hopeless of early succor, Arkansas without a soldier, and the Indian country undefended except by its own inhabitants. Availing himself of these advantages the Federal general Curtis marched from Elkhorn along White River into Northeastern Arkansas, and halted at Batesville, 90 miles from Little Rock, to get supplies for an advance on that place.
General Pike had at that time one regiment of Arkansas infantry, two 6-gun (Arkansas) batteries, one Texas battery of four guns,two regiments and several unattached companies of Texas cavalry, and ten 10-pounder Parrott rifles, besides 5,500 Indian troops. There was no Federal force, other than small marauding parties, within 200 miles of him. General Roane was at Little Rock without a regiment, and Curtis' victorious army, at least 15,000 strong, was moving in that direction. Fortunately five regiments of Texas cavalry arrived on their way to Corinth. General Roane, by permission of General Beauregard, detained them at Little Rock. About the same time, by order of the Navy Department, the Confederate ram Maurepas, Lieutenant Commanding Joseph Fry, came into White River, and the ram Pontchartrain, Lieutenant Commanding J. W. Dunnington, into the Arkansas. These accessions had the effect to retard the movements of Curtis, whose advance, when I assumed command, was 35 miles from Little Rock.
I found under General Roane eight companies of Arkansas infantry, wholly unarmed, one 6-gun battery, with but 40 men, and less than 1,500 effective cavalry, many of the Texans being unarmed and many of them sick. For this force he had about three days' subsistence and forage and less than 15 rounds of ammunition. There were no depots of supplies in the district....................