Question about Benchright Table Plans

I am hoping to make the Benchright table, but need to make a few changes for a larger family. I am planning on having it seat 8 by add some length to the table, and was wondering if I would need to change anything structurally, and if I do - what would I need to change?

Also, when comparing with the longer table at Pottery Barn's site - their longer table uses diagonal piping rather than the single horizontal pipe. Would I be able to stick with the horizontal pipe on a longer table, or should I use the diagonal configuration?

And, one more question - We live in a rather small house, so I was wondering if I could build the table to be in two separate pieces - the base and the tabletop. In the plans, the runners are attached to the base - but I was thinking that I could just build the top separately, and have the top attached to the runners, and then sit the whole thing onto the base?

I'm hoping that someone who has more building experience than myself will be able to help with my questions. :-) Thanks so much!

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