As I have said before, the reason why there is no separate guidance for the use of Earmarked Reserves is that those funds are no different from any other funds at the disposal of the parish council. They are "savings" if you like that are being built up for identified projects so arguably should only be used for those projects. In all other respects such as how these are spent, the need for comparative quotations, etc. etc. are as per your financial regulations.
A committee can have delegated power to make expenditure decisions if that is within your financial regulations and/or the committee terms of reference but the over-riding requirement for compliance with financial regulations cannot be circumvented simply by delegating authority to a committee. If your financial regulations state that expenditure over a certain amount needs full council approval, then expenditure over that amount needs full council approval unless full council decides otherwise.