Oh in the item field, the Spiria orbs you get by converting sync rate is random? For some reason what I understood was that it copied a random ability from the effects thats already present on the weapon and so you would need to find a weapon that has the ability and farm the ability off it. That makes more sense (albeit grindy) if its completely random.
Your understanding is correct. Spiria Orbs can be obtained from the equipment you started the Item Field run.
For example:
1. You chose to enter the Item Field of Celestite. Celestite has 2 EXP modifiers by default, one that gives flat EXP while another gives EXP multiplier.
2. Upon completing one Item Field run, you have 3 options to use the current equipment affinity as cost to either improve item stats on Celestite, generate a Spiria Orb out of the 2 EXP modifiers on Celestite, or unlock a modifier slot with a maximum of 10 slots available for Celestite.
Because Item Field runs can be repeated, and each run also gives affinity to all equipment used by team members in the run you can technically improve an equipped weapon of a member continuously in one Item Field sortie indefinitely at the cost of not progressing storylines since multiple runs of the same Item Field sortie is still considered as one sortie.
Item stats are improved by random and are not checked by stat limit. This means that it is possible to waste equipment affinity on stats that are already capped, ie. a 1 AP Cost item rolling stat improvement of AP Cost.
Spiria Orb modifiers are technically not random since they are restricted to the modifiers you are running Item Field, meaning a Celestite with 2 EXP modifiers cannot give Spiria Orbs that are not one of those 2 modifiers. Each modifier also has their own generation weight, meaning rare modifiers on an equipment is harder to generate their Spiria Orbs when there are other modifiers on the same equipment. Again in the case of Celestite, the Spiria Orbs that are generated from this weapon would have a higher chance to be flat EXP than EXP multiplier due to the latter's rarity/weight.
For your first run try to use equipment given through ally bond quests. These are pretty solid and contain strong modifiers enough to carry your progress through the whole game without much tinkering needed assuming you are not playing for higher difficulty challenges. Ensure your characters actually have skills unlocked through bonds and their skills actually equipped and active.
For equipment drops, modifiers can only be viewed in equipment stash so yes, you will have to collect the equipment in the item drop screen to check their modifiers. Equipment stats can however be viewed by right clicking them on the item drop screen.
when the item PRICE is high, the quality of weapon is good.
Item price is a result, not an item quality determinant. Sortie difficulty is more relevant - it determines the item drop itself, and introduces a price multiplier to the item drop if it is available across multiple difficulties. Herb Flasks will be much more expensive to sell if its dropped from Avon Farms at Ultimate difficulty compared to Normal despite being the same item, and you most likely will not see a Grass Dagger at Normal difficulty either. There is also no guarantee that Ultimate Herb Flasks will have much better initial equipment stats than Normal ones. Equipment modifiers from dropped equipment are also not random, so the only way to access better equipment that comes with modifiers is again to play harder difficulties. That said, since equipment at lower difficulties don't usually have modifiers, they are usually the easier options for modifier customization.
Is it just me or is the brothel is kind of weird lore wise, since it creates a lot of inconsistency if you consider studs affect on characters
The brothel is just an alternative gameplay mechanic that is not a key factor in the lore, at least not in determining the major decisions of the story. It is totally possible to skip the brothel entirely and still collect all CG/scenes by configuring character status in brothel management and leave them out of a sortie run.
Do the different pregnancy options have any difference? Like does it matter if you choose to keep the kid or give it to Lorona? It seems like all of the options just end the pregnancy without any other effects
Pregnancy are mostly visuals and mattered as an aesthetical feature.