8. This wouldn't necessarily cost money, but Dresden should spend some time scrolling the walls with the right runes so that Bonnie can effectively use the house as her skull. Instant Smart House, literally.
Yes! I love it. Don't see it happening but I love it lol. Harry needs at least a couple means of secret egress in the event of being under siege both mundane and magical you know pull a book on a bookshelf and it swings out uncovering a underground tunnel. Even better if in addition to a portal somewhere in the house the escape tunnel has both an exit far enough away to not be seen from the house and outside a reasonable siege area and a separate portal hidden in it. Of course if I were Harry I would have several tunnels complete with mundane and magical traps. Wouldn't stop someone from tracking him by scent to discover what tunnel but would hinder a lot coming after him. Of course that's after they battle through his defenses at the perimeter of his land and before or after the defenses of his house depending on if he wants to attempt to fight or wait them out or flee before hand. Much like a castle with a moat as its first line of defense Harry would have a warded wall and wards and other magical traps keyed to not trigger from select people ie him, daughter, Mouse, etc. Then the warded walls and whatever threshold he can get out of his house which might be more if he has his daughter living with him are like the walls of the castle. Go one step further and have wards on his floors inside to trap/hinder the already weakened creatures that bash through his threshold. Then of course he needs variants to protect him from vanilla humans. Oh and might as well throw a panic room or two in here. This is in addition to the lists that others came up with.
I play D&D so I tend to try to think over prepared. Played a rogue once that had a longsword, 7 daggers, 2 sets of lockpicking tools, bow and arrows, throwing darts, blowgun, several various magical grenade type things and a couple other specific items that I can't think of right now. 1 dagger was hidden in the sole of his boot you know spy style and one set of lockpicking tools was hidden in the other sole. 1 dagger at his side, 1 inside of each boot (bootknife) 1 up each sleeve and one at his lower back. Basically he had his main weapon the sword and several backups to hopefully not get found if searched lol. Think the DM said that it would take 10-15 minutes to fully dearm myself. So yea Harry needs to design his home like I made that rogue. Try to prepare for anything. Oh and if any of you that played are thinking about the weight for one I had a slightly high strength score for a rogue as well as the backpack version of the bag of holding, the whatever the belt of holding is called. I was rich...rogue duh I...acquired valuables.