Um... no... You cannot take a bus from a resort to the TTC. I do believe there must be buses from the parks to the TTC, because you might be parked there. This is why there is a TTC. MK is isolated. It is surrounded by a lake. If you drive to MK, you end up in a parking lot the size of Delaware. This parking lot is where you will find the TTC. You actually are not dropped off right by the MK entrance like you are with other parks. If you take a bus from a resort to the MK, the bus goes to the front entrance, area just beyond where the monorail exit lands you. If you were to park at a section of the MK lot, you might be for instance, parked in Minnie Mouse.. then you get on a tram to get you to the TTC. right? I'm confusing myself.

Yes.. I think that's it... and you then from the TTC, take the monorail to the entrance... or the boat.
Just know that when you check into your resort, the packet that they give you has a thick brochure with the castle on it. In the center of the booklet is a guide to Disney Transportation. It is laid out very well. It will say for instance... to get to Magic Kingdom... and then under that... it will list all the ways to get there. There will be an entry for each park and other options such as DTD, resort to resort.
We usually stay at Saratoga. To get to Saratoga from any of the parks, take a Saratoga Bus from the bus bay. To get to Saratoga from DTD, you can walk around the lake (there is a path on both sides of DTD) or take the boat launch. You can walk to Beach Club (beaches and cream) from the World Gateway entrance at EPCOT (there is also a boat launch there). It is really not a long walk. We could have taken the boat, but the walk is so pleasant. I do not think that there is a bus from BC-YC or BW to EPCOT which is why the boat launch. You can also walk to DHS from the boardwalk area resorts. You can also find resort maps online. If you can't find them here on the WDWinfo.com, you can look at allears.net. I know she has maps in pdf form that you can download.
It really isn't difficult once you get here and you have your handy guide. Also.. that same guide has a listing of all the restaurants, and a brief description, and information on other recreation and what numbers to call to reserve... such as golf, boating, bikes etc.