Repairing leather torn along the seam?

Hello,

I have leather on the driver's side that is torn at the seam. Unfortunately it was repaired in a rather disastrous way… see photos (stapled?) and before considering taking it to an upholsterer I am looking at the DIY route.

My question, as a complete novice:

Would it be possible to reopen this seam to place a piece of leather in it, and then apply the liquid leather as explained in the tutorials?

Also, does the new colour mean the topstitching has to be covered as well?

Thank you very much for the help!