How Can God Be Omniscient about Never-Ending Future Events?

Questions about how God can be omniscient about never-ending future events, whether the salvation of a man who comes to Christ after being dramatically changed by a brain injury “counts,” and whether one should feel at peace dating another believer who differs on whether or not one can lose one’s salvation.

• Since our time in Heaven will be endless, how can God be omniscient, knowing everything that will happen, when there isn’t a finite amount of knowledge to be known?
• If a cruel, abusive man becomes kind and gentle and comes to Christ after a traumatic brain injury, which is the real version of him, and does his salvation “count”? 
• Should I feel at peace dating another believer who differs with me on whether or not one can lose one’s salvation?