Welcome to the Strelets Forum. Please feel free to discuss any aspect of 1/72 scale plastic figures, not simply Strelets. If you have any questions about our products then we will answer them here.
Rofur flags are designed for 1/72 scale. They're out of business but you still can find them on EBay.
Co-incidentally, I just bought a lot of dozen or more sheets that included a bunch for the Prussian SYW-Napoleonic infantry units that I don't currently need but will keep for future projects.
As for Warflag - certainly. You can find divers flags from other sources by googling. A lot depends, I think, on the quality of your printer.
For some time, Ive been using an industrial quality laser printer from work that produces excellent flags. I use my own superior quality printer paper too.