If you follow the below advice, you will have enough holes in the ceiling where you should be able to fish that old wire to an appropriately located 4" light.
In a kitchen, with standard height ceilings of 8', you will need roughly (1) 4" 50w recessed light every 24" to 30" at the edges of the counter to get the appropriate working light on the counter top with an even spread.
I have been using 5" cans with 75w halogens for years now with PAR bulbs, and the newer 75w BR halogens are now used where a wider flood is wanted. Remember, a 50w par/r/br has HALF the lumen output as a 75w par/r/br. HALF. 1100 lumens on a 75w compared to 550 lumens on a 50w. That is significant, especially in a kitchen where an absolute minimum of 50 footcandles is needed for task lighting, and 75fc is where it should be. If you place the 4" cans ever 24", with a 550 lumen par/br, you will get roughly 55fc on the counter, and with good undercab lighting you can boost this to just over 70fc on the work surface. Other than sink lighting, I DO NOT recommend 4" line voltage cans in a kitchen.
Just the other day, one of the contractors I do work for asked to do a lighting layout for his kitchen, using old 4" cans that he had stockpiled. He seemed quite surprised that he needed 11 4" cans in his average sized kitchen along the perimeter of the counter. It's tough to grasp the idea that going from 75w to 50w cuts the lumen output in half.
As to what kind, I have never had problems with homeowner supplied Halo remodel recessed lights and their clips, but I use Juno and Lightolier. The Juno 4" cans have 2 clips compared to the Halo 4 clips, but they are the same style, just easier to lock in. Again, I have never had problems with either. You can get Lightolier roughly 4" cans in a different style, where the trim acts as the actual housing. There are three little anchors that you pull tight on a ring, loop them, and then slide the trim/housing up through. I like Lightolier, but their 4" step baffle trims are roughly $40, or nearly 4x's the price of the Juno/Halo 4" step baffles. Their larger sizes are the same price, but 4" is out of hand.
What exactly are the problems you are having with the locking clips on the Halo cans? Try pushing them in by hand, and then to lock them all the way in, use a thin blade screw driver and tap the top edge of the clip to push it the rest of the way in (if that is the problem you are having).