The Great Duck said:
1)Where can I see all new events added by CORE?(please give a link)
I don't think we have a listing or such. It would probably be too long anyway...

For example our Munich chain alone is over 200 events, covering both historical and ahistorical options. The overall COREd events would run in the thousands if not more, many of those interlinked.
The Great Duck said:
2)What events have been altered by changing triggers,text,name,options or option effects?
We have a few Vanilla events that have been altered, but most have been replaced by new event chains which are much more in-depth.
The Great Duck said:
3)Are there any new techs added?If they are,where can I see them?
Are you asking whether are all the tech trees are completely revised and extended upon? Absolutely.

The last count I did for 0.30 (currently in beta), excluding naval and naval doctrine tech trees, came out at 462 techs. On average about 70 per tech tree. We're using nearly all of the model numbers which can be used too. It's probably best to install CORE and have a close look at them that way. Beware though, it takes some getting used to, but once you've tried them you're bound to get hooked.
As we're using a moddir installing CORE won't affect your regular DD setup anyway.
The Great Duck said:
4)The same question as 1) and 3),about leaders and ministers this time?
A lot of new tech teams and leaders are added, and some of the former will be unlocked by event or research decisions. Plus they're historical, unlike some of the Vanilla ones. A lot of changes to those are in 0.30, though the current regular release (0.25) does contain the odd one or two already.
The Great Duck said:
5)Is CORE for HoI2 something like VIP for Vicky?
Yes, and as such we even share the same forum. Unlike Vicky we have changed the techs and models as well. But the changes to the original game are as massive as those VIP made for Vicky.
In all fairness: if you liked Vicky then you surely will like CORE!
