way to search product

-- HikaShop version -- : 2.7
-- Joomla version -- : 3.
-- PHP version -- : 5.4

Hi
Forecommerce search input form is the more important things with efficient web gui !

I have not a good view ( "architecture") about the differents fields that are searchable for one product .
To be able to search a word that is in relation with the product , this information must be create and index !
what are the different way i have now in hikashop ( add information , index , search ) ?
-1 custom fields ( all filed og joomla article plus any default fields of hikashop product ) ?
-2 characteristic ( all characteristic attach to a main product , one ...) ?
-3 category ( one item in a hiearchy , range of item in hiearchy , last item in hiearchy ) ?
-4 all fields in hikashop products ?
-5 joomla tag ( i think no same name fo category but different way to use ) ?
-6 brand ( that behave like a category ) ?

is there others ways and what are for 1 2 3 4 5 6
-the cons and pros ?
-the context of their use ( suitable ? ) ?
-the jomla extension name that override those default functionnalities ( create for for hikashop or joomla)

regard's

Yes so ... I can find on all fields of hiksahop product !