Crazyantler,
Getting your bow checked every once an a while is a good thing. Just make sure that they understand the reasons for the tuning job they are going to do. Asking what type of tuning method they use is a great way to start. What a proper shooting bow would be for them and why they set up a bow that way is extremely important to me. There are many folks out there that just set up bows by putting equipment on them but never tune the bow or equipment to match each other. If your bow is grouping well, a once over won't hurt. Keep in mind your bow is not fully tuned unless it groups.
Yes, there is a some standards out in the industry for strings. Most strings don't hurt to change in 5000 to 10000 shots and some that have to be. There are other strings on the market that will last upwards to 15000 shots. Strings do stretch, this will effect grouping and proper arrow flight. No one can say for sure without looking at your bow what truly might need done to it.
Speed is also one of the most over emphasized part of archery equipment. Just keep in mind if your shooting from about 260fps to 290fps with your hunting step up on newer equipment your doing very well and are in a great range. Not to say speed is a bad thing but it is not the most important part of our equipment. You will be much happier shooting a bow that you can shoot super accurate then a bow that shoots super fast. Though a person can learn to shoot a super fast bow, super accurate.
Hope that helps and wish you the best shooting.