Hello Courtney, welcome to the boards
It sounds like you are doing well with your lo so far, well done, especially on the sleeping through.
I will try to answer some of your questions.
In order to ensure my son's days resemble each other should I wake him up at the same time every morning and from his naps at the 2-hour mark or let him get the rest he seems to want/need?
I always think that, for sucessful naps, it is a good idea to wake them at a consistent time in the AM. That way, the timing of his first nap, and hopefully therefore subsequent naps, will be consistent - babies thrive on consistency, and it really helps with a good nap routine. With regards to waking him up after his naps, I'm not as rigid about this, but it's important never to let him sleep so long that he misses (or postpones) a feed time. Keep the 'E' timings consistent, or you really will have problems. If he isn't hungry in the early AM, btw, have you tried leaving it for half an hour? I know many people who cannot eat first thing in the morning, and many babies are the same. As long as it doesn't interfere with his first nap, try it a bit later, and see if he takes more.
45 minute naps - from what you describe, it sounds to me like your lo may be ready for longer A time, especially at 4.5 months old - a key time for developmental jumps. I say this b/c he's waking up at 45 mins and not crying, indicating that he's feeling refreshed after his nap, but then getting tired again soon after. This is b/c he's had 45 mins to make him feel refreshed initially, but then his body realises he hasn't had enough, and gets tired again. I think it might be worth you extending his A time - in 10 minute increments a day (so you're not stretching him too far and getting him overtired). This may help him get 'tired enough' for his nap, and more able to get through his 45 minute transition.
I also think that the rocking in the middle of the nap is doing you no favours. He may well be relying on you to help him transition between his sleep cycles. You'd be much better using ssssh/pat or pu/pd (depending on the temprement of your lo) to help him learn this himself. Please let us know if you need help explaining any of this, we'll be happy to help.
I hope I've helped a bit, please let us know if you need any more help/clarification, and keep us updated on your progress