lima and cusco i am only well too familiar with…so yep i can help you out….. a two week vist would do fine, theres is plenty enough to see surrounding cusco and the valleys….
now… first off, lima is a good time to go as it will be the summer, which also means less tourists, though theres always some activity going on in the centro regarding entertainment.
cusco, you would find more wet, and if you intend to go to macchu piccu then it is the wet season there, though shouldnt be a problem, it is not like the rain we get here in britian..lol
travelling, regarding lima and hiring a car…..id forget that idea, id say 85% of traffic on the roads there are all public transport and very cheap…..travelling to cusuco you have two options, bith i have done. you could catch a national coach…which takes 24 hours, a return trip for me the first time to macchu piccu via cusco from lima took in all six days by time i got back to lima, and that was a rush trip. the cost was about 15 quid aprox. just to cusco…..second option is by flight, costs aprox ?80.00 and takes only one hour, this can be booked in many of teh travelling agents that you will see in the centro area of lima.
oh another disadvantage of the bus trip, is that you gotta toilet on the coach, you will soon find out yourself, no matter where you are, peruvians have a thing about not cleaning thier toilets.
accomodation in lima can be very cheap, just matter of looking via internet, same goes for cusco and surrounding areas.
if you are heading for machu piccu, take supplies with you, you will find the nearear you get the more prices start to rise.
also, fotocopy your passport to carrry at all times, keep the original and anything else hidden safe where ever you are staying, some apartments or hotels provide safe boxes. but you will need ID for catching certain public transports such as the national coaches and trains etc.
hum… you seem to know the crack with general common sense regarding saftey, considering the palces you have been to..soo feel free to ask any thing else….