What a good roof replacement includes
A strong plan names the shingle, says the old roof comes off down to the wood, and lists the new underlayment, ice barrier, flashing, pipe boots, and vents.
If a plan is vague, ask. Two plans that look the same on price can be very different on what you get.
Ice barrier at the edges
Ice and water barrier is a sticky sheet that goes under shingles at the roof edges, in valleys, and around chimneys. It helps stop water that backs up behind ice.
North Wales Borough's permit packet notes ice shield is required on reroofing over 25%. Ask your roofer to show where it will go.
Shingle repair vs. a new roof
If the roof is fairly young and the damage is in one spot, a repair makes sense. If shingles are worn out everywhere, patching may only buy a little time.
A roof inspection with photos is the easiest way to know which one you need.
Attic airflow
Cool air should come in low at the eaves, and warm, wet air should leave near the ridge. Without that flow, shingles can wear out early and ice dams can form.
A good roofing contractor checks the attic, not just the shingles.