I think, it is suitable for you, because the centre was not so big. Or you can walk only shorter part.

I bought the tickets at the office near the park and boarded the bus some time later in the day after other things we did.

Hola, visitar el centro histórico de Lima, es tener un paseo de no menos de 4 horas, recorriendo sus calles antiguas, sus plazas, sus monumentos, sus iglesias... y por qué no sus restaurantes. El centro Histórico de Lima está aproximadamente a 8 Km de Miraflores. Saliendo de tu hotel en Miraflores te toma entre 45 a 50 minutos llegar al centro. Hay taxis, buses y colectivos que te llevan y traen.

si de noche se ve todo con luces espectacular, tipo 7 pm

I don’t know any hotels near airport. Airport area is not a good area. I recommend Mira Flores if staying one night. Taxi will cost you about 30 to 40 soles. Grab a taxi in the airport. Only authorized taxi can enter the airport.

One huge tip, do NOT use Taxis, do not use public transportation, UBER is super cheap there, and they are there within a few minutes if that long

Este es un review del centro histórico y no de un tour. Su hotel le podría organizar un tour me imagino

Miraflores is a very desirable place to stay. The Centro Historico is identified as perhaps the second best. For our part we stayed in Miraflores and we're glad that we did. From there we were able to tour to all of the other major attractions easily. Mirabus tours were excellent.

Like most travellers I stayed in Miraflores. The Centro Historico is very pretty but we were advised to give it a miss after dark.