Set a spawn point in Minecraft?

I've tried everything, including marking the original spawn point, sleeping in a bed, and dying, but the spawn point after death will not change. Any advice?

Minecraft 1.9 super laggy

My graphics details:

Card name: Intel(R) HD Graphics 4600
Manufacturer: Intel Corporation
Chip type: Intel(R) HD Graphics Family
DAC type: Internal
Device Type: Full Device
Device Key: Enum\PCI\VEN_8086&DEV_0416&SUBSYS_185D10…
Display Memory: 4153 MB
Dedicated Memory: 112 MB
Shared Memory: 4040 MB
Current Mode: 1920 x 1080 (32 bit) (60Hz)

What happens is I load a new world, and it crashes almost immediately after its creation. The fix I found that worked was to enable VBOs in video settings. However, now that I've done that my game does not register when I break a block in survival mode until 2 - 3 seconds later. It's worth noting that my graphics card has been tweaked by ASUS, and I play on a laptop. These crashes and lag did not occur in previous versions of minecraft.

MINECRAFT. How do i get home from the nether?

So, i always take my portal with me when i go to find the nether fortress. But once i have all my loot and re build the portal, it takes me to some random place in the middle of nowhere and not to my house. WHY DOES IT DO THIS AND HOW DO I GET HOME?!

Would 500 Gigs of Storage for gaming be enough (PC)?

I brought this laptop a while back 2 years ago when I was still crazy into minecraft, and I loved it. I now realise it actually is packing some pretty good beef, especially for 1100 dollars. I got fallout 4 and all of the other Bethesda games (ALL of them) and I have about 300 gigs left. If I continue to install this amount of games, will 500 gigs be enough or will I have to add some?

Do you usually switch back and forth between games?

I've had fallout 4 for a couple weeks and I'm like 8 hours into it, but I also own the witcher 3 and I haven't even started that. Should I start the witcher 3 and return to fallout 4 eventually or should I at least try to finished the main story of fallout before starting the witcher?

How to make Minecraft non-SF world deeper?

I have this idea for an underground castle in a massive cavern, but I have never found any area with enough ground depth to make a cavern with more clearance than about 80 blocks without ending up with holes in the ceiling, even under mountains and going down to bedrock. Is there any way to make the world deeper with the advanced customization settings that doesn't also make everything stretch out of proportion or something?