I'm about to head out the door but a couple of quick thoughts ...
Sounds like it's hammering. Definitely needs cleaning and oiling internally. Especially the hook area. A dull needle could contribute to that sound.
The slow start could also be related to lack of lubrication. But very often that slow start means the motor and/or foot controller need to be serviced.
This is all easy stuff to do. I'll recommend going to you tube and looking up Andy Tube he has hundreds of videos, mostly on old Singers but it still applies. Also Vintage Sewing Machine Garage.
I'll check in here later this evening and see if we have any updates from you.
Oh, the stitching is probably a simple issue as well. It starts with cleaning, oiling, checking your thread path, using new thread and needles, things like that.
It's all very Zen. Sit with the machine, go over all the parts of it, study how it works. Become One with the machine . Ommmm...