best way to concentate low-quality mp3s together? Options

[bigidiot]

Hi, there, I recorded an important interview with what I thought was a high quality audio recorder (Marantz).
Apparently I totally messed up on the settings. I used a preset which recorded in mp3 of 64 bit, and worse, the recorder automatically chopped everything into 3 or 5 minute clips. What a bother! (I read the manual very thoroughly after that!)

I need to concatenate the mp3s into a single audio lasting about 45 or 60 minutes. I haven't opened up Audacity yet, but I suspect I can just connect the tracks using that tool. When I put everything into a big track and save as mp3, will the sound quality decline precipitiously? Are there any settings I can take to minimize any degradation of quality which occurs?

This is only speech, so the quality does not have to be great. But there might be some additional sound quality issues (i.e., things which need to removed or flattened out) to deal with.

Should I make a wav of everything first, and then edit and then convert the longer file into mp3?

Thanks. Robert