Fifth.. call it something without the word coin in it.

That's the easy bit. Just call it the
hazek.
I think a new currency is a bad idea. It's fiddling around, tweaking the peripheral things, while missing the big picture.
Bitcoin won't succeed or fail depending on whether the block target is 10 minutes or 30 seconds, nor on whether its rate of monetary inflation reaches zero in 15 years or 500 years.
Nor does the risk of 51% attack really matter that much. Over the next decades, there are going to be hundreds of types of attacks on Bitcoin, of which the 51% attack is only one type (and it's by no means certain that a 51% attack will occur). There's no point worrying about about a 51% attack, except as part of a general general commitment to make Bitcoin as robust as possible.
It's much more important to have a wise, experienced, and diverse set of developers who can respond quickly to any threat that is brewing, just as Satoshi did when a hard fork was needed due to exploitation of the overflow bug. I say a "diverse" team, because a hostile takeover of the dev team is probably a much higher risk than a 51% attack.
The success of Bitcoin won't depend on its technical characteristics. These are mostly "good enough" already, and the rest are capable of improvement within what we know as Bitcoin.
Instead, the success of Bitcoin will depend on legal challenges, the global political environment, whether Bitcoin's future crises (and there will be many) are handled in a way that maintains credibility and minimises damage, whether any Google/Amazon-type organization adopts Bitcoin or whether they introduce their own altcoin, whether Oprah Winfrey endorses it, etc.
Something that already works and is "plenty good enough" will always win out over something that might (or might not) provide a small incremental improvement in the future.