1st my condolences on the loss of your dog mate.
As for the glue up, I'd alternate the grain. The width of the boards is not really big prblem,if they have been seasoned properly.
Matching the grain is just a matter laying pieces side by side and picking the best match.
If you have a good hand plane #5 etc it is not hard to flatten the boards.
As for the glue up it all comes down to the joint. The ideal is to have no gaps hence no requirement for clamps,the next best is to either plane them with a small concave edge thus a clamp in the centre will do the job or convex and use a clamp at either end.
PVA is stronger than the timber so it will hold with no reinforcing, however you may liketo use biscuits or dowels as locators.
Good luck, have fun mate.