Issue #1 ArcGIS doesn't work in the way that you would like it to. 🙂 You need to place the point and then fill out the attributes of the newly created point, you can't create a new attribute table entry, fill in Lat/Long and the point will appear. The spatial reference of your point is not stored in your LAt and Long fields, those are just fields that you would like, so you can identify where the point is.
You can however create an excel spreadsheet that has Lat and Longs and through the Import XY data make a feature service out if it. This will create a new point layer for you.
Issue #2 You could just copy and paste your ArcGIS attribute table into an excel spreadsheet when you want to update the spreadsheet.