return to work and preparing my baby for a babysitter

Hi! My daughter is almost 7 month now and in September I need to be
back to work and she will be with a babysitter during the day (most
likely the whole day, about 10 hours). I am a first-time mom and so is
her babysitter (babysitter's son is 1.5 months younger than my
daughter). The babysitter doesn't have much experience in childcare, so
we both have lots of questions. I would like to make this transition
the least stressful for my baby, and start working with a peaceful mind
(although I'll probably be very anxious anyway). I'll appreciate if
you could help me with your advice on a few questions:

1. How to introduce the baby to the babysitter? The babysitter is just
someone I found through an ad online, we haven't even met much. Does
it make sense let my girl stay with the babysitter a few times for a
few hours before I dive into work and she has to be there all day long?
My daughter is very attached to me and will probably be more attached
in a couple of months.

2. What kind of items will the babysitter need to care for my baby
(besides the regular set - diapers, bottles, etc.)? I don't have an
extra crib - does it make sense to buy one or will she be ok sleeping
on a mattress on the floor? She always sleeps on a mattress on the
floor when we visit my in-laws, but she's 7 months now and not very
mobile. Would a mattress be a good idea when she's 9 months or should I
still buy a crib for her?

3. Day schedule - it is wise to ask a babysitter to stick to some kind
of schedule (feeding, sleep)? I don't really feed her by the clock
these days, more on demand (she's breastfed) but obviously I'll have to
give up breastfeeding when I start working.

4. General issues - I don't know how to phrase this question
properly, but I would like to know what the babysitter is planning to
do with the baby and how she's going to adjust her life (shopping,
household duties, hobbies, etc.) to her childcare commitment. I
wouldn't like her to watch TV all day or take my child grocery
shopping - how should I start this topic with the babysitter without
too much interference in her personal life?

5. Any other tips and recommendations? I'll be very, very thankful
for any information you're willing to share.

Thank you in advance for all replies!