1.) When you research a new component, say a pulse cannon, it unlocks new ship designs, which are in the templates of every race. The yellow exclamation mark means, you recently unlocked a new template and have not taken a look at it yet (i.e. clicked on it in shipyard at least)
2.) This means these are specializations techs. Specialization techs are techs you have to choose one out of 3 or two of. For example after researching the hospital tech you can unlock on of three specializations: +1 production, +1 food or +10% population growth. The yellow star is meant to warn you. For example if you want to research +1 food and trade +1 production from the AI, you can't research +1 food anymore. You can research the +1 food first and after this trade the +1 production, then you have both.
3.) Can you make a screenshot next time you see this? There are some techs with very similar names, so I would guess you are mistaking one tech for another. A screenshot would be helpful.