Im in need of Kamen Rider Info

[Kogashi]

The 'best way' would likely be have all the world's kind of meshed together, like in CB Go Nagai World. Having the most important places in the series repersent that series's land... Only it might make more sense to not have them chibi-ed ^^;

Course, you could also go with how Warriors Orochi did it and have some supreme bad guy pull them into a blank world and just have chunks of land from the various series litter it.

[kkkk]

Worlds meshed together? Nah, if the worlds are meshed together, i will have to create a new bigger story.

[Kogashi]

Then I'd go with Dimension ala Super Robot Wars/Namco X Capcom (I believe). Just have it take place on one series's earth and just have everything/one in it.

[That Guy]

To have a teamup, either ignore the fact that they're in different universes or pull them all into one universe (it could be one of the rider's universes or it could be completely original).

[DaikaijuSokogeki!]

Are there any previous Kamen Riders that was killed? in the middle or the End of a series?

Aside from the Heisei Rider series, Tackle died in the middle of Kamen Rider Stronger and Riderman "died" near the end of Kamen Rider V3.

[Phoenix512]

To have a teamup, either ignore the fact that they're in different universes or pull them all into one universe (it could be one of the rider's universes or it could be completely original).

The one universe idea is how Super Sentai does their teamups.

[Saejima Kouga]

Wasn't there another Kamen Rider series before Den O to feature giant enemies and/or a mecha?

[KRendBlade]

Well, Kamen Rider X went up against a giant robot once, and Rider 1 and J have both gotten really big to fight giant monsters, but I don't ever remember seeing both ideas in a single series.

I mean, Paradise Lost could count, but that's going into spoiler territory.

[Techol887]

Hibiki fought giant Makamo on a regular basis as well

Also, just throwing in a couple of points:

Are ALL Kamen Riders in the same universe? or just same time? or what...

As mentioned already, Rider1 to RX exist in the same universe

Spoiler

Spoiler?
J and ZO shared a special but I'm not sure revived, supersized Shadow Moon is canon

Kuuga may or may not be connected. In one of the later eps there was a refernce to a Professor Hongo.
Might be a subtle hint or easter egg, depending on how you interpret it

Are there any previous Kamen Riders that was killed? in the middle or the End of a series?

Riders known to have died:

Spoiler

Riderman (V3) but was revealed to be alive in a later series
Tackle, if you consider her a rider (later part of Stronger)
Shadow Moon (ending of Black), came back and died again in RX
Another Agito (near Agito's ending)
For the Ryuki riders: Including the Tv series, movies and specials, they've all died at one point or another
Anybody who touched the Kaiza gear except Keitaro(Faiz)
Majority of the Delta users (Faiz)
Psyga (Faiz movie)
Orga (Faiz movie)
The movie riders from Blade: Missing ace
Shuki (mid-late in Hibiki)
Zanki (near the ending of Hibiki)
Kabuki (Hibiki movie)
Sasword (near Kabuto's ending)
Punch Hopper (before Kabuto's ending)
Caucasus, Herakus, Ketaros (Kabuto movie)

ERrr... Is Shadowmoon a Rider?

I'd say he was. Apart from one being good and the other evil, Black and ShadowMoon shared the same origins. The way I see it, in the older series the Kamen Rider title was reserved for the heroes

Spoiler

Like when V3 dubs Riderman the 4th rider after he sacrificed himself and Black rejecting his original name and calling himself a Kamen Rider.

So he was more or less an evil Rider before they were given the Kamen Rider name