37 first baby.. questions about safe exercises and midwife

Sonia
Hello, I am 6 weeks in to
My first pregnancy and haven't made my first appt. yet since I just found out the other day that we are expecting. Can anyone offer suggestions on safe exercises in the first trimester, can I do any abs work out or none? 
Lastly, I would prefer a natural birth and only know very little about midwife.. is midwife a separate person I need to find besides doctor or do doctors offer midwives as well? And how far in advance do I need to find one and lastly where do I look for one? Any help would be greatly appreciated.