Camelbak/Osprey/etc hydration packs are convenient for stuffing sandwiches, jackets, tools and things in and holding water, but personally I find backpacks sweaty and uncomfortable, so as much as possible I prefer to use a waterbottle and a tool roll. @BareNecessities carries my pump ;)
A small frame bag could equally take supplies and a hydration bladder. Unless you're actually bikepacking, weighing your bike down is not that fun so don't go overboard.
ATACs are fine. Flats and cheap spds are good too.
Wear anything you like. It mostly doesn't matter as long as you can move in it, regardless of what you wear it's going to get horrible and muddy, and if you fall off as much as I do, completely ruined in fairly short order. Long sleeves and trousers are nice in the winter to keep you from getting too filthy and protect you from foliage. I have some nice tough cycling jeans from ION, but stretchy jeans from H&M work well. Baggy shorts are useful in that they dry out quickly and you can wear them with knee pads, if you want to get rad. You can of course spend a fortune on Fox and Troy Lee clothing if you want to look like a motocross rider/enduro bro/power ranger and like fist bumps and making braaaaap noises.
I don't bother with padding, I find I don't need it as you're out the saddle so much, but ymmv.
Camelbak/Osprey/etc hydration packs are convenient for stuffing sandwiches, jackets, tools and things in and holding water, but personally I find backpacks sweaty and uncomfortable, so as much as possible I prefer to use a waterbottle and a tool roll. @BareNecessities carries my pump ;)
A small frame bag could equally take supplies and a hydration bladder. Unless you're actually bikepacking, weighing your bike down is not that fun so don't go overboard.
ATACs are fine. Flats and cheap spds are good too.
Wear anything you like. It mostly doesn't matter as long as you can move in it, regardless of what you wear it's going to get horrible and muddy, and if you fall off as much as I do, completely ruined in fairly short order. Long sleeves and trousers are nice in the winter to keep you from getting too filthy and protect you from foliage. I have some nice tough cycling jeans from ION, but stretchy jeans from H&M work well. Baggy shorts are useful in that they dry out quickly and you can wear them with knee pads, if you want to get rad. You can of course spend a fortune on Fox and Troy Lee clothing if you want to look like a motocross rider/enduro bro/power ranger and like fist bumps and making braaaaap noises.
I don't bother with padding, I find I don't need it as you're out the saddle so much, but ymmv.