Ok, thank you very much for the helpful comments.

One more question about calculating the necessary vBytes.

Just to clarify what I read and understand so far from other webpages:

If I want to send BTCs from my Wallet (in Legacy Mode) and
I send BTCs from x own addresses to y partner addresses and get back the change on 1 more own address I will have to pay for

x * 149 + y * 34 + 1 * 149 +-10 =  .... vBytes

Correct?