When can I introduce to him cheese and bread? Is it okay to give him foods with added salt and sugar now? Mozzarella and ricotta cheese have lower levels of sodium. Can I give him those?
Cheese and bread are fine. They do contain salt but the levels should be low enough for you not to worry about it. In the UK the shop shelf bread is higher in salt than in most other countries and for that reason I did a quick calculation for my DS and worked out something like half a slice of bread per day would be his max, this left a bit of allowance for other foods with salt such as cheese etc, I also occasionally used canned tuna (in spring water or oil, not brine) and canned baked beans, I didn't give these often due to the salt but a small portion now and then is ok. If you use mainly fresh produce and don't add salt when cooking then there isn't too much calculation to do to know how much of a food is in the safe limit.
You don't need to limit to mozzerella and ricotta, any cheese is ok really although yes some are much higher in salt than others, we are big cheese fans so I didn't limit the variety and would let DS taste anything but I wouldn't have given huge portions of the saltier cheeses. Again it depends what else LO is having in the day, I wouldn't for instance have given salty cheese plus baked beans plus tuna plus bread all in one day, but a bit of something across the week/month is fine.
Been looking at the breads in stores. All have sugar added but there are some with very little added sugar. Can babies have low sugar bread?
I hunted our shelves for bread without sugar added. I did find one without added sugar. I probably wouldn't buy a special loaf just for LO as they are not going to get through much, but if you are happy to switch to a low sugar loaf for the family then that's great as you'd have less to think about on a daily basis WRT preparing meals.
Is 11am lunch to close to naptime at 1130am?
Mine used to spend so long eating it ran right up to his nap time anyway. I wouldn't worry unless it shows itself as a problem. If you switch the 11 milk to a snack though you will likely see if he would like to eat lots (ie early lunch) or not so much (ie snack) at this time. 2pm seems like a good lunch time right now but as the nap moves later (as it likely will) you could then shift the lunch to pre-nap rather than post nap. Some do a 'split lunch' when the nap falls right over lunch time so half before nap and half after, it's fine.
I can see you are concerned about the BF prior to nap. I would do snack at 11 followed by a top up BF if you are worried but really at this age LO needs his solids meals and snacks so really now is the time to be looking at solids as his main source of food. It would only take a few days of changing up the habit if he is reliant on the BF to get him used to napping without, try not to worry (most of the things I worried about with routine changes my DS took in his stride, all the worry was for nothing!). Whilst there are benefits to extended BF there are also benefits of taking solids meals and snacks well: for calorie intake, for vitamins, and for motor and language development.
Does you think a routine like this is alright: replacing his 530pm milk with dinner.
5.30pm is often too late for many LOs to take a decent dinner but it's fine to try

If he doesn't eat much you might consider the 4.30pm dinner (in the sample routine I posted) instead and then at 5.30 (if that's our family dinner) let him join you at the table and have a few nibbles if he is interested.
hope this helps x