Question about functions and a identity Question

I have two quick questions about basic trig.My first question is asking to find period, amplitude, and phase shift of a function written as

f(x) = -cos(pi(x - 0.1))

Can i write the function as

f(x) = -cos(pi x - 0.1)?

Also I was asked to find the values of x between [0, 2pi] of the following equation

2sin^2 = 1

When i solve this equation I get

sinx = 1/ root 2

There is no special angle or this solution so would I use a decimal approximation?

Thanks for any help