It means that the instrument/contract that is being assessed will be considered a "security" under applicable laws.  This means you will need to either register the offering of that security (with the SEC and applicable state regulators) or find an exemption for those registration requirements.  

It is a rolling 12-month period.  So you can start a new one as long as you are under the threshold and you have the needed financial statements.  Usually you will need to prepare new financial statements every April 30 (for calendar-year companies)

Assuming you are asking about another CF round.  The cap under Regulation CF is applied to a rolling 12-month period.

Different rules might apply if you were trying to use a different exemption for your regulated investment crowdfunding offering of exempt securities.  

Sometimes but it really depends on your particular circumstances.

Investment crowdfunding can potentially limit future financing options due to the large number of shareholders on the cap table. When a company has numerous individual investors from a crowdfunding campaign, it can complicate future fundraising efforts as new investors may be wary of coming into a situation with such a dispersed ownership structure. Additionally, managing communication and decision-making with a large number of shareholders can be challenging and time-consuming for the company's management team.

There are ways to limit the effects of both of these concerns with planning.  For instance, a company may be suited to issued non-equity securities, like revenue share notes, or might utilize transfer agents that consolidate ownership into one record holder.  You could also limit voting rights on regulated investment crowdfunding issued securities. 

Institutional and angel investors have varying views on crowdfunding.  There has been a significant shift in "acceptance" of the use of regulated investment crowdfunding by many more (but not all) institutional and angel investors.  It may also depend on the region of the country where those investors are located. 

I'd be happy to chat more about the realities as they would apply to your circumstances if you want to chat directly.