1)i can create water wells on settlement but is there to create pure water from them for crafting

2) the settlers.i can give them stuff but how do i get to guard the settlement and equip stuff

3) are all crops located near settlements such as carrots?

4 when u help the raider drain the quarry are you supposed to wear radiation protection or is this just a crazy quest ?

1) Water wells do create purified water for crafting (each water well outputs 3 units of water). You can also make purifiers at settlements where there are sources of natural water (streams/rivers/the ocean) if you have a rank in the Science perk (the smaller purifier might be available from the start, not sure).

2) In the Trade screen you need to select an equip-able item on the settler's side of the screen and then one of the hotkeys at the bottom of the screen will tell you which button to push to have the settler equip it (think it's T on PC). To get them to guard a place you need to set down some guard posts and, in build mode, go up to a settler, press the Command button, walk over to a guard post, and press the Assign command. 1 Settler can man 3 guard posts (the 1 you select and the 2 nearest ones, this part is automatic).

3) All crops can be grown at any settlement (excluding Boston Airport), but by default, different settlements focus on different crops until you plant new crops for them to tend.

4) You might want to pop a Rad-X and have a RadAway handy, but it's quite doable, just dive where the bubbles are.

Water wells won't add any units of Purified Water into your workshop inventory. The larger purifiers will, though, but they can only be placed in water.

Dirty Water seems more rare than Purified Water since you can just use a Water Purifier to get Purified Water while you have to search the Wasteland for Dirty Water. Which seems completely ridiculous since you should be able to get dirty water from a water pump. Also, Dirty Water is used in 7 recipes vs. 4 for Purified Water. I am not including the recipe to turn Dirty Water into Purified Water.

Unless Sanctuary gives purified water automatically, water wells must give purified water since that's what I'm getting in the workshop and I have no purifiers.

So do i have to have 2 ranks in leadership to assign guard duty?

this.

I get purified water in my workbench at Abernathy farm a lot and all I have is the 3 output hand pumps...

No

No, you just need guard posts to assign people to.

Nope. Just build some guard posts, stay in build mode, highlight a settler, and assign them to a guard post and then he'll man that and the 2 nearest guard posts.