What can I do to increase leg strength/flexibility?
Stance training is the best way to increase felxinilty as well strength in kicks. Once you’ve got the basics down for footwork and stancing you should try thowing low medium strength kicks in high reps. You’re not going for power here you need technique. Usually a 100 or so on each leg is good or you can alternate 25 on each leg. After a week of that move to a heavy bag and start trying to increase the strength of your kicks incrementally until you’re comfortable.