Navigation for presentation...help!

"-Play-presentation starts first Topic and goes to certain point when it MUST stop and display last frame of what was played."
There is no way you can tell Encore to do anything other than playing through to the end once it has started playing it. Which means that the video up until the "MUST stop" position will have to be a separate timeline.
After that you will need a still to simulate the freeze on the last frame. I would suggest to use a still menu for that. Simply freezing on the last frame (or any other frame) of a video clip isn't possible with DVD-Video, with any authoring application.

"-When it is needed PUSH next chapter button - and presentation starts to play from last stop WITH NO delay or with minimum delay , but absolutely without Blackscreen. ( all this within one topic ) Then next topic starts and so on."
If you authored the freeze frame as a still menu, with an invisible button linked to the next clip, you would use the "enter", "go" or "play" key instead of the "next" key.
With a DVD-Video disc there will always a brief pause going from a menu to a clip or going from clip to clip, but usually much shorter than in Encore's preview. A set top player will hold the last frame or field until the selected item has been located and starts playing, so you won't see black in between (unless of course the last frame was black).

If it is necessary that the "freeze frame" can stay on screen indefinitely, then there may be other ways of authoring the project, but not significantly simpler ones. (At least not that I can think of.)

If however the maximum time that a freeze has to stay on is known in advance and this time is not too long, there could be an easier solution. Lets say that you know the freeze will never be displayed for longer than 3 minutes. You could then create your video so that the freeze would be part of clip and be "pre-frozen" for 5 minutes. Chapter markers would be placed just at the end of each freeze. The final DVD would contain just one clip/timeline.

When the DVD is played, it would look like a freeze frame where the disc is playing the 5 minute still section of the timeline. As soon as you hit the "next" key on the remote, the player will jump (as fast as possible) to the next section of the timeline.

Whether or not this is a usable workaround will depend on the total duration the video is already and for what time the pre-made freezes would have to stay on in total.

Not sure if I am understanding the question, but authoring for the "previous" button with multiple timelines is tricky.

Assuming that you are using version 1.0.1 or 1.5, the timelines are numbered in the order they are added to the project. Hitting the "prev" key once will jump to the start of the timeline being played. Hitting it twice in quick succession will probably start the preceding timeline. Especially for a live presentation type project, I would recommend to avoid having to using the "prev" key. If you can describe your project and its navigational structure in some more detail, maybe we can find a workable solution for it.

The way you are describing the project, it seems to be a fully linear presentation, going in only one direction: forward. Time and space permitting, it could be authored as a single timeline with "extended" stills and chapter points at the start of each new item/answer.

"Time and space permitting": e.g. if the total presentation would last 20 minutes, divided into 10 items and a 5 minute "pause" per item would be sufficient, then the total timeline would come to 70 minutes (20 minutes plus 10 times 5 minutes). This would easily fit on a DVD, without compromising quality. But if you would need to pause say 15 times for 10 minutes each, the total would come to 170 minutes. You would have to test and decide if the image quality is still good enough. (With VBR MPEG encoding that wouldn't be impossible as most of the timeline consists of stills, which can be encoded with a low bit rate - leaving more bits for the motion sections.)

What I am missing from your description is the need for the "previous" key that you mentioned before. Hitting the "prev" key twice should make it possible to back up by one item/answer. But if the person giving the presentation doesn't double-click fast enough, it will restart the same question twice instead. To avoid confusion during the presentation, my suggestion would be to add a menu with links to all the items. If the speaker needs to go back to any of the previous items, he/she can hit the "menu" key and select one from the menu.

Another possible solution: If the total presentation isn't too long (roughly 20 minutes or less) you could author each item as a non-looping motion menu. The time constraint is because the combined menus on a DVD are not allowed to exceed 1GB. The ~20 minutes should fit without quality compromise in this 1GB.

Each item would be set up as a non-looping menu with 2 or 3 invisible buttons: e.g. #1 to advance to the next item, #2 to go back and #3 as "panic button" to go to a main menu in case the speaker has lost his way or someone in the audience wants to go back several items. Navigation would be via the number keys on the remote.

As the menu holds on the end of the video background, you would automatically get the indefinite freeze - without the need to "pre-freeze" like I suggested earlier.