K.,
First, yes just water in the sippy cup and take out the valve if it has one. Let her get the hang of it without the valve and then when she is a little older she can try to introduce the valve slowly.
As for the food. It took my daughter 7 weeks to get up to a 3 meal a day schedule. We did breakfast, then added dinner and finally added lunch. You can either nurse before the solid food or after whichever you prefer but she will still need the nursing. Breastmilk should be her main source of calories til she is 1 year old.
My daughter got cereal and fruit at breakfast and veg and fruit at dinner. (Our dinner was at 5pm though - enough time to try something new before she went to bed) this is something to think about when adding new items to your babies diet. Any chance you can give her a little food at daycare before you leave for home- or if she doesn't go to bed til 8:30 or 9pm then you should be OK. Check with your ped but I think you are supposed to have 2 hours before you put them to bed if you have given them something new to eat. Or speak to the daycare maybe they can give her some dinner at 4pm or so.
When my daughter started on lunch I would always introduce new items at lunch time - it just made it easier. Now she gets yogurt - Yobaby whole milk organic plain yogurt with separate fruit for breakfast - she loves this. Veg and fruit for lunch and cereal and fruit or veg, protein and fruit for dinner - it depends what she is in the mood for. She doesn't seem to be big on the proteins. My daughter is 9-1/2 months and didn't start with proteins until she was 9 months old.
Hope this helps and check with your ped if you have any concerns,
Enjoy the fun,
L. M
PS - she might soon start to grab for the spoon - let her have her own. Sometimes they also want to feed themselves. I put a very small amount on the spoon my daughter has and at first helped her put it in her mouth - now she can do it. And as she gets older - around 8 to 9 months you can start to introduce finger foods. Gerber puffs that disolve in their mouths, cheerios, pieces of cheese things like this but check with the doctor if you have any questions. Also T.B. Brazelton has a book called Touchpoints. It is really good and talks about feeding and I found it very helpful.