Hi! Congratulations!
A couple of thoughts:
PAIN:
I only found that it hurt when I had a small infection starting - but that was VERY easily taken care of with something called APNO (all purpose nipple ointment). I also developed mastitis once, but it was also taken care of with an antibiotic. I know that the reason I got mastitis was because I didn't drink nearly enough water while we were away for a long weekend at my in-laws' - you have to stay hydrated! Other than that, I have never, ever had any pain. I've always heard that if you're feeling pain, it's likely because the baby just isn't latched correctly.
BOTTLE / PUMPING:
My first did take a bottle of breastmilk from her first few days on. I think this was one of the best things we ever did! It allowed my husband to feed her once a day and gave me a break. (I still pumped at that time.) Around 4 months, we also started giving her a bottle of formula before bed - also allowed someone else to put her to bed beside me - also one of the best things we ever did!
My son, however, had more trouble latching and took a long time (4-5 months) to take to a bottle, so we ended up never getting him started on a bottle for bed rather than nursing - but I do wish we had.
As for how much to pump if you choose to, when I went back to work (babies 4-5 months old), I've always pumped about every two hours! It probably sounds like a lot. If you can get a good set up (i.e., have pump plugged in, ready to go) going so that you can be efficient, it's not so bad. As the baby grows and you incorporate solids into his or her diet, you won't need to pump as much - you can drop pumps as you would drop nursing sessions. For example, if you replace a nursing with baby cereal at 9 am, then drop your 9am pumping. My rule of thumb has always been - if baby is getting a bottle of any kind, I pump. If food, I can drop that pumping session. (ps. I did find pumping to be a little uncomfortable at first, but now it doesn't phase me one bit.)
EVERY BABY IS DIFFERENT! -
My son has taught me that every baby is DIFFERENT! Nursing has been a pretty different experience than nursing my daughter. She was a "comfort nurser" - lots of cuddling, dozing while nursing so it took a long time - which was fine since she was my first. Sometimes I felt like all I did was sit on the couch and nurse, but looking back, I'm thankful to have had those few months with her - just the two of us! My son was just the opposite - he was a fast and furious nurser - done in 5-10 minutes! He too loves to cuddle, but not while nursing. This made it easier to nurse with a two-year old daughter running around. On the other hand, he had much more trouble latching than she ever did, so this made nursing him more difficult. Also, she weaned at about a year with NO PROBLEM. He is another story.
NURSING IN FRONT OF OTHERS:
I totally understand your concern about nursing in front of your sons and other family members. I never wanted to nurse in front of others either. With my daughter, I have to admit that I did find this rather isolating. Like I said - she was a "comfort nurser," so feedings took a long time.....which meant longs stints by myself in a room. Sometimes a sister would join me, but I do remember saying to my husband that I was devoted to nursing but it was isolating.
With my son, I did nurse him in front of my daughter, but she wasn't even two yet when he was born. Your sons are older, and I don't think I'd feel comfortable nursing in front of them either. Depending on how long it would take to nurse your new baby, would you feel comfortable leaving the two boys alone with something to do for a bit? Now, when I put my son to bed (15 months old), I leave my 3 year old daughter in the living room with coloring or a short tv show, etc. until I come back. I leave the bedroom door open so that she can peak her head in if she needs something, but she knows to be quiet!
I hope this helps! Overall, I have LOVED nursing. It's a lot of work, and sometimes, like anything that takes work, it can be frustrating - but also very rewarding for both you and baby! At the same time, plenty of people try to nurse and find that they can't (not enough supply, for example) or that it just doesn't work for them). Whatever YOU decide will be right for you and your family. Good luck!!