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The answer to the first question about strumming is to practice strumming in isolation. Mute the strings with the fretting hand and spend 5 mins a day on trying to strum without so much force. Make sure you are just using the tip of the pick and angle it up or down depending on the direction you are strumming. Go slow to start (this is the hardest thing for me).
The 2nd issue is similar. Try isolation by just placing your fingers without strumming, do this slowly for five minutes, then add strumming but keep it slow. Slowly increase your speed over time. I highly recommend using a metronome. If you make mistakes 3 times in a row then slow down the metronome. Once you can go 3 times without mistakes increase the tempo by 5 or maybe 10 bpm. Rinse, repeat. Depending on the challenge you may get up to speed in a single practice session, but more often it will be several days or weeks to get up to speed.