The batteries you could try to source Lead somewhere local, but not great. LiPO4 would be ok, but the ones from Cell_Man are a123 (super high quality), but relatively expensive [you gave no indication of your range]. I would read up on the options from Cell_man, he's a bit slow to respond too. You didn't indicate much else.. and the only thing I can suggest is that reading more on ES because everything demands on your needs.
The donor bike not being great does not necc mean you want a cheaper bike setup, since you can install the kit on a new bike if you get a new bike.
New to endless-sphere? Notice a lot of signatures recommending Ebike.ca? That's because it's the best place for a quality and manageable, (but still 'real'), first build. Justin is a solid supporter of electric bike development, and a good source of equipment.
My hat off a thousand times to the green people that effectively run this forum. The ES Mods are superb.