With my build, I couldn't max all the skills before Purification. I just got the minimum requirement and maxed Purification. Maxing Spirit of Holiness would be nice though.
Elemental Protection is mostly a PVP skill. It's rare to ever use it outside or in Coliseum unless you don't want to save a few pots once in a while.
The same goes for Hand of Holy Spirit. Mostly a PVP skill and I found just level 1 is good enough.
You can enter Expert at your level and be level 190 in no time. However, it's rare to see parties recruit low level Minstrels since they know low levels tend to not have enough skills maxed. If you party with friends, the skills above are useful. If not, I would hold off on learning them until you do decide to do full Expert Coli runs.
Really, the build is up to you on what you want to learn/what path to take. Without taking Water skills, I do believe you can go down both trees. You'll have to do some calculations to see how far down you can go.
I prefer Energetic Performance. Buff them to give them more damage means faster runs. Defense has it's benefits too but with the speed my party kills, I can heal enough in combination with the free HP/MP heal from clearing a certain stage.