You say you haven't bought it yet, so:

1) do a home inspection (or have one done) to ascertain exactly what the condition of the home is. Most often, finding the right inspector and paying for the service is money well spent, even for building professionals.  If you don't hire someone, compile (or find on the internet) an extensive checklist to address all aspects of the home.   For example, some questions that need to be answered are:  What condition are the well and spetic in (if applicable)?  Is there significant hidden termite and/or moisture damage?  Is the foundation and structure itself in reasonable condition, or is it litterly ready to fall down having 2x4 20' rafters or is one corner sinking onto soft soil?

2) Make a list of each major item that needs to be redone and formulate a budget for each based on research - not just wild guesses.  The basis of the task list will be the home inspection report.  Prudence would dictate that these first 2 items will be completed before even buying the house.  Renovating a house can easily be expensive as building a new home, and you need to be sure you know what you are getting into - money wise.  This will also help you define your rather large task and slice it down into smaller manageable tasks.  Really, you are going to need significant liquid funds available to proceed with this project - unless you AND YOUR FAMILY are willing to live like you are in the 1940s for years until the bulk of the project is complete.  This step will also help you determine if this particular house really has the bones that are worthy of the huge task at hand.  

2.1) Do your research and come up with an overall plan that includes what each wall system, floor system and roof system will consist of.

3) Weather proof (water proof) the exterior of the house and renovate whatever exterior items are not sound - i.e. roof, siding, foundation, etc.  If you have water intrusion you will just be throwing away time and money by doing interior improvements that may get damaged by moisture.

4) Do your plumbing, HVAC and electrical renovations each as a separate project and in their entirety to bring these thee items up to current code.  Pretty much in that order too - based on what feasibility each of those trades has in placing their fixtures and supporting systems.  For example, if you place wiring in the way of where a toilet pipe needs to go, you will be redoing your wiring work and wasting time and money.

5) RE insulation, be aware that if you want to use spray foam insulation, it isn't really a DIY friendly project because of the equipment required.  There are DIY kits available, however to get the complete job done, these may be as expensive as getting a pro to come in and "knock it out" all at once. You will pay a SIGNIFICANT premium if you have a foam contractor come back several times to do one or 2 parts (rooms) of the house at a time - because of equipment setup and cleaning charges.  If you use foam insulation it will make a significant impact toward transforming an old drafty structure to a modernized and comfortable home.  If you use fiberglass insulation the task can be done 'piece-meal' but the end result won't be as "snug and secure" as the spray foam route.  Be aware though that spray foam may be 2x the cost of fiberglass or cellulose insulation.  Also be aware that often an insulation contractor can insulate a house for the same $ or slightly less $ than you can buy the fiberglass/cellulose material for.

6) Then start your room by room restoration.

Some general thoughts re using forums like this one to get information:  Once you have a general plan in place, limit your posts to one topic or a few related questions.  You will find that when you ask a large number of questions you will only get maybe about 1/2 of them answered.  Spend some time formulating your questions so that all the pertinent information is provided and make an effort to leave out extra, unneeded comments or text.

Lastly, using sentences that start with capitol letters and end with punctuation, usually a period or question mark make your text much easier decipher.  It is generally accepted that sentences are preceded with 2 spaces.  Paragraphs are used to set apart major topics and are often preceded with a blank line.   To not heed these items will cause you to loose a percentage of your target knowledge base from the start.