Does OpenLiteSpeed support Server Side Includes?
OpenLiteSpeed 1.4.x is not yet supporting "server side includes". It is a planned feature for 1.5 branch. LiteSpeed Enterprise supports "server side includes" since 4.x version.
Does OpenLiteSpeed support .htaccess?
No. Only LiteSpeed Enterprise support .htaccess. However, OpenLiteSpeed does support rewire rules. You can enable rewrite rules in virtualhost or context of virtualhost section.
Does OpenLiteSpeed have QUIC support? if not will it have QUIC support?
Right now QUIC is for LSWS enterprise only. There is no timeline to offer QUIC support for OLS yet.