Hi Venelin,
first of all, don't hesitate to ask if you have a question!!!
Basically brushes go with all types of colour, so no problem here. Windsor & Newton is a very serious company and all their products are recommended. I use their watercolours, oils, lacquers and brushes for many years to my full satisfaction. Sorry for babbling!
What you may consider is this: figure painting as an "artform" and painting figures for dioramas is not entirely the same.
In a diorama the figures are only one part, while a single figure on an elaborate base is all there is!
When I paint single figures, I go into the 5-tone technique, while the 3-tone (+/-) is sufficient for diorama "participants".
What I'm after is this: while figure painting may require only the very best (and expensive) brushes, the diorama "branch" can easily do with cheaper ones...not the hairy ones from the shop around the corner, but synthetic hair ones f.ex.!!!!
I've used them for around 20 years and I've never regretted it!
They are comparatively cheap and they last forever!
Give them a try!
Cheers
Romain