Neither Canadian made Tiger Moths I have flown had any spin strakes, I understand it to be a national choice as to require them of not.
Yes, the optimum spin recovery technique will vary by type, and is usually published, even for some non spin approved types. I've never flown a Chipmunk, so have no comment on that type, but I can say that moving the controls forward progressively on some types will delay the recovery. I erred into doing this while spin testing a modified Cessna 206, and had a heck of a ride. For the next spin, after recalling the wording of the POH, I moved the control wheel "briskly" forward following rudder application, and it recovered nicely.
Take training, and read the applicable information for the type.