More newb fermentation questions

I am working on a batch of Blackberry wine, I started with a SG of 1.090. At transfer from crock to carboy I had a SG of 1.030. Less than 3 weeks later, essentially all bubbling has stopped and I have a SG of .992. Is this about normal?

I just siphoned and racked for the first time. Is it safe to cork or should I still airlock and if so for how long?

Taste aside would the wine be "safe" to drink now?

Also I am shooting for a quite sweet country wine and will probably add sugar. Would it be prudent to do it now or at a later racking? and is there a specific gravity indication of how sweet a wine is or is it merely taste?

Thank you guys. Much appreciated!!

Sounds normal, I would let it sit on airlock for a few more weeks if there is no space in your container. If there is any residual co2 it could pop your corks. If you want to speed up the process, you can degas it. The wine is safe to drink. It always has been. Just not tasty.

If you want sweet wine, you need to back sweeten it. This means killing off the yeast and preventing further fermentation before adding sugar. When you do sweeten, just go by taste. Do a small test batch with measured amounts of wine and sweetener.

That's extremely dry imo - you might want to consider a little back sweetening. Other than that you're bang on!

My blackberry wine finished at .990, where I like it. But I needed to rack it a couple of times, as it dropped lees for several months after fermentation was over.

Don't be in a hurry to bottle it. Let it sit, so that it clears and the sediment drops out. Rack off of the sediment every 60 days or so, or whenever you have lees 1/4" thick. Keep an airlock on it, and keep it topped up.

When you are ready to sweeten the wine, stabilize it first with campden and sorbate by racking into the appropriate amount (usually 1/2 teaspoon sorbate per gallon and 1 crushed campden tablet per gallon) and let it sit for several days. Then sweeten to taste, and let it sit for several days. If you're certain fermentation hasn't restarted, you can bottle at that time.

Remember that stabilizing only works if the wine is perfectly clear, and there are no fresh lees!