Both hotels are on the pentire headland overlooking Fistral beach and I would say about 15 minute walk into town which is a bit hilly.Can't comment on the pentire hotel but we used to stay at the esplanade, great location, good fascilitys and food, haven't been since 2005 so can't say what's it like now but by all accounts it's still good.
The Fifteen restruant is at Watergate Bay which is best reached by taking the back road past the boating lake, through Porth, over the hill down into Watergate bay( the Newquay to Padstow coastal road is fantastic). Never stopped at the Watergate bay hotel but it all looks impressive and you walk straight onto a great surfing beach so might be a consideration for accommodation.No idea about taxi fare but I reckon about a 5 mile 20 minute journey from pentire so it could be around £20 but best get quote from a taxi firm.