Hiatus hernia redo operation

Hi all, a number of years back I had a repair operation for a hiatus hernia I think by Laparoscopic Nissen Fundoplication procedure, by keyhole. To cut a long story short, a couple years ago after an illness my old symptoms started coming back and after having an upper endoscopy my surgeon has told me the wrap has partially separated and I need another repair operation, his report is as follows

Apparent mucosal junction at 40cm from the incisors.

STOMACH. Post-Surgery; a fundoplication - appearances of partial separation of the wrap.

Oesophagus - Normal

Stomach - Post-surgical

Duodenum - Normal

I am due to go into hospital on 22nd September to have surgery but do not know what is involved and would like some advice please, some people say they go in and just do a quick repair and add more stitches etc, while others say they have to completely remove the old wrap and start again? I can't find any information on the redo procedure.
Any advice on the operation and what to expect during and after would be most appropriated, i.e how it is preformed, how big an operation and recovery times etc.

Also, I have noticed the last few months when I lift my head in a lying position I get a raised bulge in the centre of my stomach above the belly button, the area around there is also slightly tender. Is this related to the hiatus hernia or something different or nothing at all, should I mention it to the surgeon when I go for my pre-op appointment? Thanks for all your help Andy.