ESA / pension & savings allowed

On previous thread by someone else i asked about pension and incapacity benifit that is not counted as income when your move happens from incapacity benifit. Yesterday i was informed that as my son has been claiming incapcity benifit pre 1995 uninterupted his pension income which is well over the £85 per week allowed before reductions are made when normally people move over to c/b ESA from incapcity benifit. But as his pension is currently disregarded as income will any savings he and his wife have also be disregarded during the transitional period? And if so will they continue to be protected as long as hes in the support group? I understand when his move to c/b Esa is made his ESA will be taxed regardless of what group he eventually finds himself in. What differences are there with regards to the two gropus, wrag and support group regards income and savings? Am i right in thinking you have to be in the support group to be intitled to have no deductions re your pension income? and at what stage do they start to ask questions regards income/savings? Is it during the transitional period when they decide which group you will be in or after this decsion is made? Sorry to list so many questions in one post and but im still trying to understand this minefield despit previous help.