Some discovery questions before I head out

Hello commanders,

Been playing elite on and off for a while and I’m completely engaged again (FYI playing in odyssey). I’m making my first journey out to Colonia and still have some questions after doing a lot of reading online I would appreciate some help with

1. When I open the system map I can see that objects have either “First discovered” or “First mapped”, etc. and I understand that when I look at my nav panel unexplored means I have not gone to them/used my FSS. In odyssey after I run my system scanner if planets have already been discovered there is no point to use my FSS on them if they are not earth-like/water worlds right?

2. Simile to my question above if I find an earth-like/water world (or ammonia world I hear) and it has NOT been mapped yet, is it always worth my time to go and map these planets?

I believe that’s my main concerns (just don’t want to be missing credits by making a stupid mistake). If there is any other advice/tips you would like to offer that is more than welcome. Safe flying commanders, o7

Edit: any recommendations on sights to see on the way out to colonia would also be appreciated. So far I have Thor’s eye on my list