Solum Regeneration (or whoever it actually is) always seem to like to design (and, occasionally, actually build) "pretty" facades with out much concern for the railway behind them. The Redhill scheme still hasn't got off the ground at all, with everybody having waited for about 18 months for any significant news whatsoever (including local councillors) and now they're out of sync with all the other town centre works; rumour has it that a start date will be mooted "soon". There's much disappointment as apparently they'll now have to build over the Princess Way car park without offering a new one, and the whole thing is basically a very small ticket office with a massive block of flats and a wedge of Waitrose in the corner. The Epsom scheme is all very well and good but effectively it's just a Tesco, Costa and big block of flats plonked over the entrance to the existing station, still with a significant number of vagaries unimproved within the station itself, including a subway which floods, bizarre lift access from the platforms, and staff and toilet facilities which don't appear to have been overhauled for a number of decades.
If this is the level of competence shown then I should think the core of Guildford's operational station will remain very much the same for at least the medium term, unless there are major planning details showing otherwise, and you'll probably be waiting some time for the entrance and flats to be built/rebuilt anyway. The last update on the main Solum site about the Guildford works dates from late 2014. I don't deny that Guildford already needs a significant overhaul, but I'm not holding out much hope that this will do everything that's needed, including simple things like (again) staff accommodation on the platforms, properly-insulated waiting rooms, signal visibility in selected places (Platform 2, I'm looking at you) and control of the public right of way. Everything else is just jam on top really. As for the traffic and highways issues, though I do visit Guildford fairly regularly (for work and leisure), I exclusively visit by rail, so I'm not really an expert on that bit.