As we near the end of 2015 we also near the end of the 4.4 LTS. This has been the second LTS release and it has been supported by the LTS team for a little over a year - meaning 4.4 has been supported for over 2 years in total. However, as announced previously the intention is for 4.6 to be the next LTS and we are now announcing that formal LTS support for 4.4 will stop at the end of the Jan 2016.
More or less. This signifies the end of our commitment to provide bug fixes and security patches for 4.4.If a security issue arises and we feel that it is easy and safe to backport it then we would still put out a release. The same goes for a bug fix. However, we no longer commit to doing so.
It already is. I was under the impression we had 'announced' 4.6 as the next LTS but a quick consultation with Uncle Google reveals this was less clear than I thought. However, it has long been our intention for the LTS team to maintain 4.6 as the LTS once core stops supporting it. Hence, although the LTS team is not yet supporting 4.6 we already regard 4.6 as the LTS because we have committed to ensuring it remains supported for a longer period.
The priority with the LTS is ensuring that it remains secure, and we generally continue security releases after we have tailed off patches. Other than that our priorities are to backport bug fixes, and provide developer consistency. We try to treat performance issues as bugs and include fixes within the LTS - but we will avoid performance fixes that seem too risky.
There is no one answer to that. 4.6 will have security support for at least another year whereas 4.7 security support duration is unknown. But there are a number of improvements in 4.7 that are worth having, in particular with regards to scheduled reminders and de-duping performance. If you go for 4.7 you may have to upgrade again a bit sooner but you'll have the advantage of the latest features.
If you are developing new features, payment processors, or extensions it's usually best to work against the latest code.
In the case of the 4.6 LTS vs 4.7, there is a specific issue that may affect your decision. An improvement in CRM-16483 (aimed at extending the ability to use smart groups within the context of the api and search builder) was applied in 4.6.6; However, it is causing some errors for sites that use a largish number of smart groups, so work is ongoing for a complete resolution (CRM-17213). In order to provide more stability for such sites, it is my intention to REVERT the CRM-16483 fix in the first LTS release. Simply stated, this means this specific set of improvements won't be available in 4.6 LTS. Sites that require that functionality will need to upgrade to 4.7 to retain it. Both the extra group-related functionality and the issues it causes will affect a minority of sites. However, I feel comfortable choosing stability over functionality in this case for the LTS.