I have been using Raavad strings (1 full blue per corner) to tie the Radzyner method, is this kosher? Also, I use which ever blue string comes to hand to make the windings, is this OK?

There is actually nothing halachically “unkosher” about using Raavad strings with the
Radzyner tying method. Many view the two issues as independent, that is, the
determination of how many strings of blue to use is based on certain considerations
versus the determination of how to tie being based on other factors. Of course, there
are those who see the two issues as “intertwined” such that the number of blue strings
and the way to tie reflect a more comprehensive approach.

So the bottom line is that your present tzitziot are 100% kosher, however if you are
trying to follow the Radzyner’s method to the fullest, you should be using the
Rambam set of strings. The Radzyner Rebbi in his book Ptil Tekhelet (pp. 115-124 in
Sifrei HaTekhelet) spends 9 pages discussing the issue. He comes out saying that his
opinion is to hold like the Rambam, however he notes that this is a difficult dispute
and one who followed the sheeta of Raavad or that of Tosafot “wouldn’t lose”.

As for switching sides: ideally you want to have the shamashim marked (tie a knot at
the bottom of the string) and only use those to wrap (i.e., one designated white
shamash, and one designated blue shamash). However this does not mitigate the
fulfillment of the mitzvah (i.e., aino maakev), such that if you picked up different
strings each time to do the wrapping, your tzitziot would still be kosher.

– Mois Navon.