10% is nice. 20% is better. I, personally, have around 35% of my pre-tax income going into savings. After accounting for taxes, I think I'm saving roughly half of my income. That is what the road to early retirement looks like. Admittedly this is made easier by me having a higher than average income, but the point remains that I am living far below my means and that this is a very good thing financially.
Such a high savings rate is probably not possible for a "poor university student", but it may become so in the future and it's a good idea to get into the mindset of saving being a major thing you allocate money for up front rather than merely something you do with your leftover money.
Indeed. BOGO sales can be great, but think first about how quickly you will actually consume it all compared to how long it will take to spoil. Canned foods that can sit on a shelf for years with no problem? Exploit the sale for all it's worth and stock up (within reason). Milk, fruit, meat, and other perishables? Sure, take advantage of any sales, but keep the quantity down to what you will eat quickly.
Yeah, cheap stuff can be a nice up front savings, but there's an element of "you get what you pay for" to consider. In some cases, buying cheap can cost you more in repair, maintenance, and replacement costs in the long run.
This is also true. Most of the things for which quality is a major concern aren't really things a broke student should be buying anyway. I'd say the best course is probably to get by on whatever cheap stuff you can for now, and save up in the mean time with plans to switch when you have enough to go straight to "it'll last forever" stuff.
This should be part of a more general policy of deliberately setting money aside up front for all your really big and important expenses. You really don't want a shortage of money at bill-paying time to come as a surprise, and it's very easy to do that if you don't plan your spending.
The quantity of dishes is largely up to preference and whether you ever expect many guests, but I definitely agree you should get permanent washable dishes. The reuse will pay for the higher initial expense over time.
More accurately, frequent restaurant eating is a good way to make sure you're always broke. If you do eat out a lot, then fast food is actually probably the cheapest option.
Home cooking is preferable if you can manage it. I'd suggest getting a few good, cheap, healthy (yes, all those in combination do exist) recipes, making large batches of them, and eating a lot of leftovers. Have two or three sets of leftovers running at a time so you don't get too sick of eating the same thing for days on end.