Update:

Done quite a bit actually. Took down the Deacons of the Deep which was an interesting if easy boss battle. I ran into Patches at Firelink Shrine and realized he was selling Catarina Armor which I picked up, only to explore the Cathedral of the Deep again and run into Seig's descendant in a well.

Found the last fire switch and battled the Abyss Walkers. Was a cool concept but the fight could have been a bit more difficult. I actually think the first phase is tougher than the second phase. Explored the Catacombs which was a poor man's DS1 Catacombs mixed with Sen's Fortress, though the Red Phantom Invasion with the guy wearing Tarkus Armor and later learning his sword was the freaking Fume Knight sword from DSII was pretty tough. With that said, the bridge part was actually cool and pretty cinematic for this game. Ran into Anri and killed her cohort Horace who went Hollow, though was intrigued to learn layer he may have been working with the Sable Knight chick. Didn't like the look of the worm and the barrage by arrows so I left.

Speaking of which, Yoel died and was replaced with this Sable Knight chick who really wants me to murder my sorcery teacher, which I'm going to ignore. I also ran into the Moon Chick knight who was friendlier this time around so perhaps I didn't tick her off like I thought.

Beat Wolnir which was an eerie but pretty easy fight except for the immortal undead he keeps summoning, luckily the fight is like Nito in DS1 and he had a bad habit of killing his own troops. Decided to explore the lake area again before leaving and not only can I summon my red phantom now, I found what looks like the ruins of Izalith and a freaking hard Demon King boss who whooped my ass a dozen times thanks to his AoE fire attacks. Finally took him down after what felt like a dozen tries and felt kind of bad to learn that demons are nearly extinct now in the series. Course I have a hell of a time against demons, so my empathy was short lived.

Been trying out new weapons as well. Really like the Abyss Walker sword since it comes close to my playstyle from DS1 but the weight is an issue at the moment and I feel like the lighter and more combo friendly Long Sword i started with is still ideal, especially because it's the weapon I'm the farthest along to nearly mastering. I'll probably explore the other part of the demon ruins tomorrow.