Shifting issue

I just recently bought a new 2007 aveo, and when I first got it, it shifted beautifully, but now I'm having some issues with it, I've got about 1,500 miles on it now, and it seems the car has a really hard time going into gear, I up shift at around 2,500 to 3,000 rpm and sometimes it takes me a couple tries for it to go into gear, and also when I'm down shifting, if I don't double clutch it, it will almost never go into gear. This is about the 6th manual transmission vehicle I've owned, and I've never had this difficulty with a vehicle, I was just wondering if anyone else's does the same, or if you had any ideas. Also, when I take off I can hear a slight rattle from the front end

Also, I've noticed going down the road, I get a loud whine, I was thinking it's the tires but I couldn't say for sure

Also, another thing I was wondering about, when I first start it cold, it runs on high idle for a few seconds and then comes down, while its on high idle, it's fine, but as soon as it drops down I can hear several popping noises in the exhaust (I'll pop 6-12 times, then stop, and run normally), but again, it only does this when you start it cold.

Rest assured the high idle at start time is perferctly normal they all do that..the thump thump noise you hear is also normal its the exhaust system just releasing some overnight pressure..both are normal. The shifting issue is normal too..it is a small engine and it shifts at high rpms...very high. No need to worry. As you use the car the shift will break in better.

my car used to be a hard shift but now everything is smooth. i remember when i first got mine that it was tough as well but now its all good. although if after 7000 miles its still shitty i would take it in