If crown doesn't fit right, can it make bit uncomfortable? can it also possiblely invisiable to dds?

Yes, and no: Yes, if a crown doesn't fit correctly, it can be uncomfortable.. The bite can be off, the margins may be open, and the contacts can be too tight or open. The crown can also be over contoured, making it feel 'too big'. These are usually correctable by a small adjustment, or by remaking the crown. Your dentist, via radiographs or physical exam, should be able to detect all of the above problems.

Crown: new? old?: Can feel somewhat new, different and uncomfortable in the beginning. At some point, a crown should feel completely natural and without any discomfort or problems. A crown may look and fit fine and you may still feel something different at first. If your dentist can't explain to you why you feel something or can't correct it within a reasonable amount of time, consider getting a second opinion.