At that age, both my kids were taking about 4 oz every 4 hours. Yes, I agree with you that it's a great idea to have her eat her solids at daycare so you are still getting lots of nursing time at home.
For what to send: I would send two 4-oz bottle since she will be there 6 hrs. Then send some frozen 2-oz bags of milk, so if the need to supplement a little more, they can. I used a schedule kind-of like this (mine was an 8 hr day, but might be similar to yours):
8:30AM - nurse at daycare one last time
11AM - 4 oz bottle
1:00PM - solids (whatever solids you are giving her)
3:00 PM - 4 oz bottle
Pickup time - nurse immediately
My kids would take any bottle. But, for my sanity, I used wide-mouth bottles with slow-flow nipples. Wide mouth bottles, because they help keep your baby's latch wide, like she latches on to you. And slow-flow because breasts don't change flow rates as babies grow, having bottles change flow rates as the baby grows is just a marketing thing.
Some babies are picky about bottles, so don't buy a lot of them at once. Just buy 1 wide-mouth bottle and see if she'll take it. If she likes it, then buy more of those. If she doesn't, buy a different one. We personally used Avent and Gerber, but as I said, my kids weren't picky.
For pumping, make sure you pump at the same times that you would normally nurse if you were home, to keep your supply high at those times. If you don't get enough pumping at work, you may need to add in one at home. First thing in the morning is a good time for this, if you can find the time, because your supply is highest in the morning.