I would suggest firstly that you tell him you are not comfortable with him staying at your house overnight and that other arrangements will need to be considered. Also let him know that you intend to bf and as such there isn't very much point in him being there at night anyhow as you will be the one who has to get up regardless and him being there isn't really going to add very much too it except make you both tired when he could get a good nights sleep and then have baby for you in the day when you need to sleep.
How do you feel about him being there during the day? Is this about him being in your home or about nights?
Breastfeeding is something you do on demand. If this is your first one you will quickly discover (no-one tells you before hand) that baby will feed at least every three hours and may take as long as an hour to feed. So in reality that is around 2 hours between feeds. Bf babies don't go by the three hour rule that bottle fed babies do too, so you could be feeding more than this. However the good news is you will likely have a much happier baby if you bf, especially at night where you can simply roll over, pick up baby and let them latch on, rather than have to stumble around turning on lights, finding bottles and making up formula, warming it up, steralising bottles etc...
I bf and i couldn't express very easily. Also bear in mind that you are then giving that expressed milk to the baby via a bottle which is a different experience for the baby than breast is. Some don't like it, and some prefer it and might reject the breast as a result. So please don't think or listen to people who say that expressing is easy or something you should be expected to do to make like easier for others or for yourself. Think carefully and weigh up your options.
As to how much time baby should spend with dad, the answer is short but frequent. If he can come by a couple of times a day and stay for an hour or so, or take the baby out for a walk (even if it's just round the shops to get some shopping for you) then try and go with that.
Remember that if this is his first baby he will likely have no clue as to feeding routines, that expressing isn't something you can just do, and just how tiring it can be, more so if baby is not a good sleeper. You need to sleep when baby does and will pretty much be a zombie for a few months on a routime of sleep for a couple of hours wake for a while, sleep again...
It's good that he wants to be an important part of babies life and you should do all you can to encourage it if possible, but if you're not together you really need to sit down now before baby arrives and work out how you both see this working and the practicalities of it all. And be prepared to change everything once baby arrives and the realities of parenthood sink in!
Good luck
Gilly