16 tooth front difference is normally the limit of the front derailleur. You might be limited to 38 tooth inner depending on you crank sets BCD. But you'd check both things depending on the specifics of what you have.

If I had a race in 2 weeks I'd take it to a shop now. I could do the work but I don't like it if it takes longer than expected and I start getting stressy if the shifts aren't great. I'd assume the shift will be a bit clunkier if you are at the limit of the derailleur anyway.

Chain rings work in pairs so get the same make model of what you already have so that the tooth ramps coincide properly.