As to amounts of breastmilk, babies don't need to increase the amounts over time (after 6 weeks) and the body changes the contents. This means you can't meaningfully compare formula amounts to breastmilk amounts.
With mixed feeding, babies easily take more than need as they can't suck without swallowing which then causes them to suck again. Normal amounts are 25oz a day with a 19-30oz range.
Just like formula feeding it's really easy to overfeed them without realising.
I started of with a bottle a day from 3 weeks, but only because I returned to work part time at 5 weeks and full time by 4 months.
I can honestly say that if I have another one (and get decent mat leave) I will have no pumps or bottles in the house. BF go through natural fussy stages, but when your mix feeding the temptation is think they'll go off boob and stick to bottle only.
You also need to watch out for bottle preference induced nursing strikes and maybe be prepared to not use bottles, when they're difficult to feed to ensure you stick with mixed breast/bottle feeding, if that is your aim.
I felt under pressure to let DH feed her before bed, but honestly the added pressure of trying to fit an express in the mornings was a right PITA, so overall don't think it helped ME. Did a whole night off once, that was great.
Depending on your fridge, you can store milk up to 8 days, personally we go for up to 5.
As for how to express (both boobs/one boob), really just whatever works best for you DCs feeding pattern. It's also variable, so sometimes you'll get 7oz and the next day (exactly the same conditions) you'll get 2oz. Some people express for a set time, others until they get to a certain amount. Just get your feet up, read a magazine or watch some telly. You can also express at the same time as your LO feeds. It is possible, I couldn't do this until she reached a certain size.
For feeding in the day, we determine how much milk she should/we would like her to have. So if it's been 3 hrs we offer a little over 3 oz. If she's happy afterwards we leave, otherwise we (I should say DH) offers more.
hth