Cutler Rolltop - basic restoration questions

I have a Cutler RollTop desk (not a reproduction or modern equivalent), very good overall condition not much required to bring back 100%. I have a few questions, but I must admit my woodworking / restoration skills are at beginners status, so be gentle.

1) The drawer locking "rod" that tabs into the rear of the drawers when the rolltop is lowered has been lost, not sure how complex this mechanism is, I would like to replace what is missing so it works. How does this drawer lock system work?

2) The the desk has been looked after, so the oak only requires a light clean and polish. It has a nice "golden" colour now (not dark as I have seen in other desks) so just a buff up should do. What products should I use and how?

3) It has only one cosmetic problem, the desk surface has a large square area of raw timber where perhaps at one time a blotter or leather inlay may have been fitted, at least that is what first comes to mind but there does not feel (to the touch) to be a rebate or cut-in to fit an inlay. Any ideas? Should I see if an inlay can be fitted or resurface the desk top. That would bring the problem of matching the current tone or colour of the top with the remainder of the desk.
I'm in Perth, any recommendations to a local company who can fit inlay or restore the top.

Photos can come later if required.
Any help appreciated - thanks...