You only having a week is perhaps going to be a problem to see “Scotland”. Nowhere looks very far but it all takes a long time, especially up the West Coast as it is mostly single carrageway roads.
From Glasgow you are probably going to waste too much time going much further north than Loch Lomond or Loch Katrine (basically the Trossachs National Park). Worth spending a night around here (avoid doing so in Crainlarich which is a touristy dump). The Arrochar “Alps” are not too challenging if you want to walk up a mountain (our mountains are small at around 3,000’ to qualify). A nice wee hill called The Cobbler is considered the jewel in the range for it’s setting, even thought it is tiny.
Museums are well provided for in Glasgow - my three favourites are the Kelvingrove, the Burrell Collections and the new Transport Museum with attached tall ship. All are free!
Glasgow is a pub culture and has many fantastic examples - everyone has their personal favourite and so will the Glaswegian you are travelling with. That said I would insist he takes you for a pint and a dram in The Horseshoe Bar - officially the longest serving bar in the UK and a great pub. Any pub that is going to suggest it has a good range of whisky is going to have well over a 100 different to choose from - I would strongly suggest you allow yourself to be guided by the barman if he is good into areas you will not find easily outside Scotland, and discover what you like that way. If you start ordering drams over 18 years old though do ask the price first, as some will have a heavy price-tag!
I would definately recommend a day in Edinburgh - it is only a hour away on the train each way so an easy day trip. If you are going to visit Edinburgh Castle pre-book and go as early as you can and go mid-week to avoid especially the afternoon/weekend crowds.
Edinburgh also has the Royal Yacht (okay only if you are into royalty things) and the world class and newly refurbished Museum of Scotland. If you want good views over the city over the Forth and into Fife, then Carlton Hill or Arthurs Seat are easy climbs in stout shoes only and accessable from the city.
For pre-reading, especially if you like odd off the beaten track things then I could not recommend highly enough buying “Scotland The Best”. Pete’s guide is the only one many Scots keep in the car and use themselves. Not your usual guide to areas but lists with reasoning of - for example - the ten best fish and chip shops in Glasgow, or the best ten beaches in Fife say. Really excellent inspiration.
Enjoy yourself and come for longer next time.