Pretty much all of the moor you can pitch a tent on overnight, but there are some horrendous laws to do with fire, so your best bet is a stove like a trangia or the likes.
The weather on Dartmoor is very unpredictable, make sure you have clothing and kit to see you through most situations.
There are walks up and around Grimspound, Haytor, GreyTor Rocks and Hound Tor, if you are into climbing bring a set of stickies as there are some very good rocks for bouldering on that circuit (Bonehill Rocks).
From Bonehill look down into the valley that contains Widecombe In The Moor, about 2 Km's to the south there is a campsite at Cockingford, that is where we normally hold the Dartmoor meet, when we get a chance (normally in May).
Be aware that any monies that you need take with you, there are very few cashpoints if any in the villages on Dartmoor and although they may give cashback they don't with all cards.
Mobile phones, IIRC the best reception is normally under either Orange or Vodafone.
Maps for the area are OL28 which is the 1:25,000 of the area. For 1:50,000 look for the Landranger series 191 (Crediton and BoveyTracey) and 202 (Torbay and South Dartmoor). Alternatively you can go to OS Select online and select Widecombe to center the map on and it will Give you a map of the whole of Dartmoor in 1:50,000 scale.
I hope this will be of use to you
