As with anything, consistency is the key.
1 - Toilet training. Puppy pads are excellent, most large pet stores will sell them. Leave them by the back door and as soon as you see your pup go to the pad, pick them up & take outside to the back garden. Lots of fuss & a treat or 2 - ham, cheese, puppy treats from the pet store, when he/she gets it right & goes on the pad or in the garden. If he/she makes a mess that clean up the mess. NEVER SMACK YOUR DOG. After eating or playing always take your dog outside, but give it time to go to the loo. Initially feed 3 meals a day, breakfast, lunch & dinner, gradually reducing them as the puppy grows older. Basic Training - The short answer is training classes, this will show your dog who is the pack leader & will also socialise it with other dogs, injections will be required first though. Neuter your dog too, preferably by age 2, no earlier.
2 - Supplies - Food bowl, water bowl, bedding, some old piece of clothing that you no longer wear, (preferably unwashed so it has your scent on it to leave with the puppy when you go out), collar, a harness will probably be the best method for you, a lead, several chew toys from any major pet shop & a crate or secure room in which to leave the dog., as well as several packs of training pads.
3 - Leaving your dog alone. - there should be no problem with leaving your dog alone. Make sure that he/she has had plenty of exercise before you go, leave the bedding & something of yours either in a crate - if that is what you choose - or in a secure room. I have never considered using a crate, both our dogs remain in the hall, with no other access to any other rooms in the house while we are out, but they always have their bedding & a few toys. Initially I left something of mine - an old jumper - as my staff/boxer cross suffered with anxiety when I left her - due to a previous owner ill treating her. Thankfully, almost 15mthslater she is pretty much over this & knows I will be back. There are some excellent Kong toys available, which make excellent chews, but also have hollow centres that you can fill with treats, which will keep you dog amused for several hours as he/she tries to get the treats out of the toy!
4 - Harness or lead & collar - See item 2
5 - Treats - there are plenty of healthy dog treats available from any large pet store. Certain human foods such as grapes & chocolates are really bad for dogs & can essentially poison them. Our dogs get any scraps left over from dinner, they each have a carrot while I'm cooking dinner & adore cheese, crisps, ham & sausages. Vegetables are excellent forms of nutrition for dogs & bananas make a great treat if your dog will eat them - 1 of ours loves bananas the other looks at you as if you are about to poison her!
6 - Crates or not - As I said earlier, I have never used a crate, nor would I ever consider it. Both my dogs sleep on our bed - which can be a bit of a squash, but I wouldn't have it any other way. If you want to use a crate, then ensure that you leave the door open so the dog can go in & out at will, leave it's bedding in there, something of yours & possibly a cuddly toy. Initially, wrap an old fashioned alarm clock in the blanket, the ticking will sound like it's mother's heartbeat & will stop the puppy pining too much when you first bring it home. If the dog has decided to go in it's crate, then leave it be, think of it like you wanting some space & going to your room - the last thing you want is people barging in when all you want is some time out. Make sure you play/exercise your puppy last thing at night before you put it in the crate, this will ensure it is tired & will just want to sleep, hopefully allowing you all to sleep too.
7 - the guinea pig - I would probably suggest you don't allow the dog into the room when it is out. It won't harm the dog & will prevent the dog from giving the guinea pig a heart attack. We have 3 cats besides our 2 dogs & they all get on great, but not until both dogs had received several left hooks off each of the cats - just to let them know who was top dog out of the 5 of them!
Remember your dog will have it's own personality, just like people, always be calm & firm when telling it off & don't allow it to do anything your not happy with. Good luck & I hope you enjoy your new pet.