Hi and welcome!
1) Unless your piggies are out on the lawn a lot for most of the year, you do not need to worm. It is not a major problem with piggies than it is with cats and dogs. I don;t worm.
2) I use fleece with a towel underlay for my indoors piggies, but there are alternatives like fitch to shavings. Not heard of verdo, so I can't comment on that. Guinea pigs need hay (preferably first cut); it should make up 80% of their daily food intake.
3) I would recommend a half yearly or yearly vet check. It is advisable to do a weekly health check and weigh-in yourself. We have got a thread about piggy body quirks at the top of our Daily Care section which will help you to determine what is normal and what is not. In the same section you can also find a thread about early signs of illness. The sooner you see a vet about a health problem, the better the chances of recovery. A piggy that is not eating quite right or losing more than 50g in a short period should ring your alarm bells.
Wea slo have a recommended piggy savvy vet locator on the top bar for our UK members.
4) I am mainly feeding Burgess Excel pellets; they are not the top brand, but are a reasonable balance between quality and price - and with two dozen piggies, I go through quite a bit! They are also widely available. We are currently in process of updating our pellet brand information and there should be a new overview thread at the top of our food section soon.
5) Guinea pigs are group animals; they are not wired to live on their own. if you are in Britain, you can make use of our recommended rescues locator on the top bar. All these rescues operate to a high standard and you can be sure that any piggy is healthy and guaranteed not pregnant; they are by far the safest place to get piggies from and not have an unpleasant surprise.
They also offer bonding with a rescue piggy under expert supervision, so you don't have to worry about coming home with a piggy that doesn't work out. While your friend's girl is undergoing a 2 week quarantine at your place (please have her vet checked and also sexed - you'd be amazed at how often the gender is not what it should have been!), you can organise a date and adoption with a rescue. You can look at both a neutered boar (which many rescues now have) or a suitable sow; a cross gender bond is the most stable of them all and can be very loving. The key to a happy piggy bond is character compatibility. Letting your piggy choose who they want to get on with will ensure that!
https://www.theguineapigforum.co.uk/threads/faq-companionship.37654/
https://www.theguineapigforum.co.uk/threads/importance-of-quarantine.108034/
https://www.theguineapigforum.co.uk/pages/guinea-pig-rescue-locator (These are the rescues we can guarantee; any others, you are on your own!)
6) Cage/hutch size: Two guinea pigs (the same as one) should have a minimum of 2x4 ft ground space on one floor as per RSPCA minimum recommendation, ideally more. if you are looking at a hutch, you need to have winter protection (either in a protected space or with plenty of insulation) and also be able to give suitable cover from the worst heat/direct sun during heat waves, as piggies can die from heat stroke.
We have got lots of information at the top of each of our Care sections; have a browse and don't hesitate to ask any questions you may have.
Ps: with members from all over the world, we are grateful if you added your country, state or (for the UK) your county/general area, so we can always give you the appropriate advice and recommendations straight away. Click on your username on the top bar, then go to personal details/location.