1) is the $375 filing fee for annual or lifetime?
2) I have done a decent amount of research including speaking with attorneys who say I CAN put a TM next to the name and that filing with the USPTO isn't necessary albeit advantageous.
You have to file a trademark declaration of use ($100 per class) or renewal ($400 per class) between the fifth and sixth years after your trademark issues and a renewal fee $400 per class). I agree that a PTO trademark filing isn't necessary but it has so many advantages that it is foolish not to do so. You cannot just put a TM next to your name and have magical protection without conducting an appropriate trademark clearance and this only works if you are already using your name in commerce to brand goods and services. I repeat--this is not a cheap or do it yourself job, and it is a mistake to try to cut corners on this.
The renewal fee is in the 10th year---so there are additional fees between the fifth and six year and tenth year. This is still an incredible bargain.
Asker, whoever you are speaking to is giving you questionable advice. If done online the filing fee can be $325 or even $275 and it just covers filing, and even then only if done under Section 1(a) rather than Section 1(b). You will need a statement of use (in fact, likely several over the life of the trademark) and timely renewal, each with a separate fee. Even so, trademark registrations are a great bargain and almost always a necessary business expense, often foolishly ignored based on faulty knowledge.