1. The sm 58 is basically the 'lowest common denominator' mic... It owns the $100 mic market. Great... They advertise a lot and sell tonnage at guitar center. So does Fender Squire.... The 58 is very strong - one reason sound companies like them. They just don't sound very good.
There are some good alternative choices in that range but when compared against what you get in the 150 -300 range, none of those mic's stand up including the 58. Personally for my voice which is thinish, male tenor the Audix i5, 6 and 7 work very well. They make a 58 or beta 58 sound muffled. They also have better feed back rejection. My PA front line mic's are om5's which at around $160 a unit are a very good choice for my band. We have a lady singer, robust male tenor and my thin tenor voice.
2. IMO, the best method for selecting a mic is to get 3 or 4 of them on stands, set the channels flat and walk between them singing. You will hear the one that sounds better. Then investigate the feedback rejection qualities as a mic that sounds great but feeds back is essentially worthless in a live environment.
3. You will want something to practice your mic technique with. Some amplification. I would recommend a powered speaker to go with your multimix. The powered speaker can also serve as your vocal monitor if you join a band with a PA. The better the speaker, the better... I have the same mixer stored in a rack bag with a stereo EQ. I pull it out for casual or open mic scenarios where there isn't a demand or the space for my digital board.
4. We have a live sound forum. That is where this thread belongs... Just sayin'