rmr1923

your current fitness level (as well as the terrain and weather) will dictate how fast or slow you ride more than anything, so just ride at a pace that's comfortable and won't wear you out too quickly. i used to wear a watch with a built-in heart rate monitor but stopped wearing it because i found myself focusing on maintaining a certain heart rate rather than just enjoying the ride.

as far as taking breaks between rides, some people will take a day off entirely, and some will do a "recovery ride" on their rest days. i mix it up and do a little of both, sometimes taking a slow-paced recovery ride the day after a long ride can be just as beneficial as taking the day off. my recovery rides are usually the days i ride with my wife, she's more into leisure riding so we'll just roll along at about 16-18 km/h, take in the scenery, and just enjoy being outside.

stretches........ you should be able to find some good resources online for stretching, but i've found it beneficial to increase flexibility in my hamstrings, IT band, and hip flexors. core exercises like planks are good also. i have to stretch often because i'm not very flexible by nature, so if you're already a flexible person then you can probably get away with just stretching during and after your rides. and i've heard conflicting stories on this, but i've been told that rather than stretching a lot before you ride, get on and ride at a moderate pace for a few minutes, then get off and stretch a bit, and then continue riding.