Sorry to hear your not having a very good time!
Most scopes (except the really high end stuff) come with a 'standard' crayford focuser. Not that its a bad thing, but they are primarily intended for visual use, and TBH when most people get into serious imaging, they tend to change the focuser as one of the first steps, alot of the quality replacement focusers come with a weight rating as to what they can happily accept, and they are built beefier. I use an Orion ED80, and i am luck, as in the person i bought it from, sorted the focuser right out, so if it wont stay, then look at replacing it, i am sure the experienced imagers on here can point you in the right direction.
As for reaching focus, this is always hit and miss, with my Orion ED80 i can ONLY focus the shot with the camera attached via the T-ring and it wracked out, visually it will only really come to focus when using a diagonal.
not much,. but i hope it helps
