Congrats Jay on the kris and opening the door to this rich world of tosan aji ("sacred metal"). I myself have only recently started to learn about keris and looking forward to learn more in this forum.
To share about my learning journey so far, while this forum has been an invaluable part of my study, I would suggest reading some books/literature for a more structured foundational knowledge base. I find the list of books compiled by Alan to be hugely helpful (
https://www.kerisattosanaji.com/keris-information). Of note from the list for me would be the books by Solyom, van Durren, and Haryoguritno which I hugely recommend if you can find/borrow a copy of where you live. They also cover the kris-making process as well as some amount of the spiritual/belief system behind kris.
on your keris:
dhapur (lit. 'kitchen' or general structural design) nagasasra (luk 11) - a ganan (i.e. those with a fauna carving on the gandik/front face of the blade) design where the body of the naga is fully formed and follow the blade (there's other naga designs of salira, tapa, siluman, temanten, etc.), typically luk 13, but can also be luk 11, 9 or even 7 (more specifically called 'naga sapta'). as Alan mentioned, 'sasra' comes from 'sahasra', an old Javanese word that mean one thousand. There's an interesting folklore on this particular dhapur - purportedly the thousand scales was made to represent one-thousand kris blades required to 'ruwat'/cleanse the land of Java after the curse of 'condong campur' kris in the Majapahit era.
The naga in your kris has a crown so some would call the dhapur to be nagaraja (raja='king') - in this case it is a Kreshna's crown (in Javanese version of mahabharata shadow puppet design), there are also specimens that use Karna's crown. However, as Alan mentioned, please don't be overly concerned about the terminologies as it differs from place to place and from group to group.
the kris definitely missing its gonjo, which likely to be of wilut design which would've contain the greneng. this is unfortunate as the form of the greneng and gonjo overall design can contribute valuable information on the 'tangguh'/ estimate of when the kris was made.
the blade is of mataram/jogja/ngento-ento style, with medium undulation and medium blade proportion. I dare not do an estimate of its age, but the luk design reminds me of a nagasasra kris I own, luk 9, made in the 1990s by the late empu djeno from Jogja (of ngento-ento tangguh tradition).
to my eyes this kris has a fine workmanship with good proportions and carvings - would be great if it can be cleaned and re-stained (warangan/arsenic staining) to bring out its full beauty. Judging from the lines I think the pamor can potentially be pedaringan kebak or illiring warih (flowing water) as well, though indeed as Alan mentioned usually krises complex carvings keep simple pamor.
likewise, if you have the opportunity, it would also be great to give the keris proper 'sandangan' (clothing). Does the kris come with a scabbard? Seems like the deder (handle) is in the jogja style and still in good condition, but the mendak/ring is rather in poor shape. The remaining hilt can thus follow the same Jogja style - mendhak (ring) and the warangka (scabbard).
I'm not sure if the above are accessible where you are, perhaps there are kris-lover community who can help with the cleaning and restaining (I recall there are threads in this forum for DIY methods as well). For refitting/creating a new scabbard I suppose you'd need to travel to Jogja/Java.