Sorry im so late in reply, it is a 5-10 min stroll on a fairly gradual incline and I too have dodgy knees and breathing issues. But there are plenty benches and cafes on the way to sit and admire the sea view ! Or you can walk along the beach.

The sunbeds are paid about €15 euros/day and have small shed near them with people that charges you, but for €10 you can buy parasol in the shops near the beach that you can keep the whole holidays and leave in the hotel, is what we do. The water activities Ive seen are many like from kayak and stand up boards to big inflatable structure on the sea that you can pay from €5 to €10 a day to use. Also wake board, kiteboard and that one you stay in a parachute while a boat hold you. Also the flying water jet board. All paid i dont remember the prices.

Definitely Albuferia

If any of the group have difficulty with steps Albufeira is better because there is an escalator down to the beach.

Nearly always 25