Hi if you are thinking of doing a engine swap it is never straight forward - I know this from past experience, ancillerie components may be different, sensor plugs / wiring may be different. That is if you intend to keep to the same engine size !!
If you intend to put a larger engine in.. well that is totally different. the wiring loom in you car will probally be different for the replacement engine and that is just for starters, there are so many variables that will take time to sort out and you won't be able to use the ecu system that is present for the engine fitted at the moment.
I would recommend you think hard about what you intend to do because you may require a donor car to use things of off the do a transplant to a larger engine size.
don't forget to replace timing belts and water-pump on replacement engine before you fit it (easier to do when engine out) and also check the clutch replacement would be the best option (it will save you work at a later date).