How customizable are attributes/skills?

Newbie question alert!

I thought I knew the answer, but I read a few confusing posts.

Since this game is so new, I am sure I am making big mistakes in attributes and skills and such. Once you choose a Profession and a secondary can you fix mistakes in attributes and skills?

Say you made a basic W/M and you concentrated on Hammer Mastery and Healing Prayers and you choose skills to support this choice.

But later you decide that you despise hammers and want to use a sword and a shield and drop hammer mastery attribute and focus on Tactics attribute and choose skills to support this.

And so on.

The point is that by level 20 you may have a completely different idea about how to play your W/M and you want to try that instead.

And what if you wanted your attributes/skills for the hammer on some advantures and then another attribute/skill focus other times. Can you switch between multiple sets?

refund points will allow you to redistribute your attribute points

skills are drag and drop without any penalty among the skills you have aquired so far (only in a town or outpost)

edit

if you are going to switch from say pve to pvp it would be better to have 2 or more specialized characters as anything unlocked by your rp character is permanently available to ANY pvp character you make and refund points while renewable do not allow for constant change back and forth

You can change everything except your primary class.

My ranger/monk is level 17 right now. Last night we had an area where my ranger skills were far less useful than my monk skills. I dropped my beast mastery down to 3, dropped marksman by one, then inflated both my healing prayers and the buff skill (can't remember the name.) Basically it turned me into mostly a monk, sans divine favor. We were much better off with me playing mostly-monk and it worked out to some extent. The transformation cost me a total of 7 points.

After we were done I was at 22/24 points. I then just rearranged myself back to where I was and was at 15/24. In 2 hours I was back to 24/24. It's very simple to restructure based on a specific requirement you might have.

Thank you so much for the replies!