There are many options.beyond whats already been mentioned:
As far as full suites, Power Producer from Cyberlink may also be a canadate to check into. Although I do not know much about it. i believe this app is capable of doing all your asking for, although it is a program you must purchase.
Nero is also capable of the same thing. Through its NeroVision program.
Also a paid program.
Another option: As far as taking a raw file and converting to DVD, one of the easiest most versatile apps is ConvertXtoDVD.
It can take most any format, avi,mkv,mp4,wmv, and many others and convert and burn to DVD complete with title menus. It does a fairly good job too.
It will not allow you to alter each file however, only make a title and menu structure for the files you add making a dvd out of them.
You can also load each avi as a sep. title, each title having chapters, and burn to dvd that way.
You must purchase it however, but does have a 30 trial to test it first.
Other more complicated methods for authoring a file could be something like MEGUI.
You can cut videos into segments, and encode them however you like. Then splice everything together to make on file. Youll have the option of saving as a MP4,MKV,M2TS,AVi or whatever you choose.
You can even upscale each DVD to 720P or 1080P if you desire, and set it for AVCHD compatable mode. the result can be burned to a DVD or DL-DVD using IMGBURN for playback in a Bluray player as HD video.
you can basically do anything you want.
I believe HANDBRAKE is similair and capable of the same, but i am not 100% sure.
This works well, and is free but will be rather difficult & time consuming to learn if you know little about the encoding process. Every step must be done manually, down to creating and editing the scripts for encoding.
You will still need something to convert the file to DVD format however to burn as a regualr DVD.