Your studio is quite small, best suited for tabletop work. And maybe headshots.

In addition to stands, you could use some space saving solutions as

Auto Poles:
http://www.bhphotovideo.com/c/product/560207-REG/Manfrotto_432_3_7BSET_432_3_7B_Deluxe_Autopole_2.html
(Autopole is something you put between floor and ceiling and you can fasten lighting gear etc. to them with
for example with super clamps http://www.bhphotovideo.com/c/product/371927-REG/Impact_KCP_700B26_Super_Clamp_with_Standard.html ) You can put autopoles closer to walls than you can go
with regular stands.

wall booms:
http://www.bhphotovideo.com/c/product/546663-REG/Manfrotto_098B_098B_Wall_Mounting_Boom.html
http://www.bhphotovideo.com/c/product/256847-REG/Manfrotto_098SHB_098SHB_Short_Wall_Boom.html

That's a pretty small area for anything other than tabletop work.  For people you need at least 3 feet but better with 6 between the background and person plus close to 10 more for you to work with.  Light stand will take up 2 feet on the sides or more each so that only leaves a small area for your objects.  Most people will say get alienbees if you are in the States or Elinchroms for international.  The new alienbees einstein lights look good although I haven't used them.  The smaller lastolite hilite (5x6) might be good for the size of space you have.  Some easy to use reflectors (translucent, gold, white, silver) or a 5-1 will be useful.  Radio slaves would be good too, I have the impact ones and they seem pretty good although I haven't had a chance to really test them out yet.  The old alienbees ones miss fired occasionally but maybe that's fixed with the new ones.  The 100mm 2.8 IS macro is a good choice too since it's very sharp.

  Whatever strobes you buy, make sure they have a fan in them. The heat is what kills strobes. You can get great deals on used equipment, but make sure there's a warranty, and a new flash tube and modeling lamp. Umbrellas don't work for still life unless you like seeing a little umbrella in all your shots. For still life, you want to be able to soften the harsh light that comes straight out of a strobe. You can use lumilux ( made by Rosco) or some other diffuser. The ideal would be a  4x4 silk scrim ( matthews or mole-richardson). They last forever. You'll need c-stand with a clamp head to hold it. With this you can use the light very effectively. Sometimes you want to blast the light straight in and fill with a silver or white card ( get them at an art supply store, or the Set Shop ). But other times you can try "feathering" the light away from the object a little bit, which gives a nice roundness and evocative light. Since this is microstock, of course you'll fill in the shadows, but don't do that until you see what the main light is doing. Since you're in the studio, try to shoot tethered so you can really see whats going on as you set up a shot. Keep going til you get the best shot you can. Don't send in 10 versions of a shot, send in one great shot ( my opinion). If you try to cut corners you'll end up with a flat boring light. You can also cut little pieces of silver cards and use them to fill in small areas. You can put them behind drinks to make them glow. Another thing that never gets mentioned is little blocks to prop things up. The best is a good quality hardwood kids block set ( all the sizes are the same, so they work together). Plexiglas blocks also come in handy. Armature wire ( get it at a sculpture supply) helps hold things where you want it, and it stays where you bend it. A-clamps, C-clamps ( sears has the best), sawhorses, a good heavy 4x4 tabletop ( 3/4 plywood, best quality), and sand bags. These are some things that make your life a little easier. Attention to detail is the key to good still life. The advantage is that your subjects don't talk back or work by the hour, and don't complain when you gaffer tape them or shoot a staple into them. BTW get gaffers tape and a staple gun.