Re: Pakistan to India
last year my fiancé made the trip from pak to agra to see the taj mahal.
he had to get a visa from the indian embassy in islamabad. it took a week or two to process, so keep in mind that you'll have to make two trips if you don't live in ISL. also, before u go there, try to find out abt the days and hours the embassy is open for business to save urself unnecessary delays.
he took a PIA flight from karachi to delhi (2 hr trip). your mode of travel from delhi to agra would depend on when you want to see the taj (dawn or mid-morning?) and how many days you intend to stay in agra. from delhi, you can either take a taxi to agra (abt 4 hrs drive, or more, depending on traffic), or you can take the shatabdi express which will get you from delhi to agra in about 2 hrs. the train is very convenient, clean, comfortable. note that the shatabdi is a 6 am train and u will get to agra around 8 am. from agra cantonment, u can take a taxi to the taj. there are other trains that go to Agra also, but the Shatabdi is the fastest train in india, and moreover it's more upscale than other trains, it has AC chairs and includes breakfast etc.
the Taj complex opens at 6 am, and if u want to see the Taj at that time, then i suggest u get to Agra the prior evening. the Taj looks different at different hours of the day because the light filters through the marble differently. if u want to have exclusive time with the Taj, then i suggest u go as early as possible. up until 7:30 am, there will be hardly any tourists there. come 8 am, the rush begins!
the other place worth seeing in Agra is the red Agra Fort. take out a coupla hours to see it.
beware of the touts. agra is full of them. u can't throw a stone without hitting one of them buggers.
as far as places to stay... coupla years ago i stayed at the Taj Hilton. i found it to be very clean, comfortable, hospitable.. and the food there was excellent.
lastly, i believe only kingfisher flies into agra and they are pretty expensive, a round trip would cost u abt USD 200. moreoever, if the weather is bad, and u are unable to land due to foggy conditions, u will be diverted back to delhi! so it doesn't make much sense to fly Delhi-Agra.
good luck with ur planning.. if u need any help such as booking a taxi service, or a seat on the shatabdi, or whatever.. pm me... i can give u the contact number of good vendors i have used in the past.