Watercolors are tricky to use at first since it's such a free medium but you get the hang of it with practice. There are some great tutorials on youtube by profesional artists if your interested.
Yah why not. Once I will master a little bit the pastel oils, I will try some watercolours. And I go on youtube a lot, to see some speed paintings. Like this, I piked up some interesting tricks, especially with acrylics, my favourite medium.
A lot of people say acrylic is really hard to use, I had a lot of frusteration with it until I discovered it could be treated like guache then I liked it.
I don't know, I never had any problem with acrylics. I just bonded with this medium as soon as I started to use it. I don't really like gouache, it doesn't have really bright colours, compared to acrylics. Yah, you are right, it's possible to use acrylics with a lot of water. I do so when I need a basic background (water, sky or far away land). I also really like to use thick acrylics without any water at all. That gives the painting the texture, the bright colours and more pronounced look, a little bit like oils. But compared to oil paint, it dries really fast.
It's always good to explore some new media. I'm having fun with oil pastels right now, want to try oil paint some time, but don't feel ready for that yet.