Hello.....my name is XXXXX XXXXX I will be happy to assist you with your electrical question. My goal is to exceed your expectations on Just Answer!
1) Since a portion of your home does not have the existing means of an equipment grounding conductor, ie, metal conduit or a bare copper grounding conductor for some branch circuits, the best recommendation is to either use GFCI circuit breakers for those branch circuits in question (if your main panel is a breaker type) or to use a GFCI receptacle and then wire the downstream receptacles from the LOAD side of the GFCI as 3-prong receptacles. The use of a GFCI breaker or receptacle will not provide you with an equipment ground, but these will protect you against any potential shock hazards. If installing either a GFCI breaker or GFCI receptacles, then the "non-grounded" receptacles along the LOAD side path must be labeled as "no equipment ground". If your main electrical panel is not a circuit breaker but using screw-in fuses, then you will need to use GFCI receptacle type.
2) Correcting the hot and neutral reversal is a fairly simple process. Turn the circuit breaker or Fuse to OFF. Back out the receptacle. The hot wire (usually a black wire)needs to land on the brass screw and the neutral wire (white wire) needs to land on the silver screw. This will correct the hot/neutral reversal situation. If you feel comfortable in working on electrical, you can easily correct this. If not, then suggest having a local licensed electrician correct the problem.
3) The electrical code does not address the orientation of receptacles. They can be installed in either a horizontal or vertical position and the ground plug on a 3-prong receptacle can be in any direction. However, most common in the industry is to have the ground plug in the top position when installed in a vertical mode. If installed in a horizontal mode, the ground plug is usually to the right hand side.
4) Even though the tester shows proper grounding on some of your 3-prong receptacles, this does not guarantee that they are really grounded. The 3-prong cube tester that you are using will not detect any "bootleg" grounds. A "bootleg" ground is when the receptacle is grounded to the neutral wire. This is a code violation if installed this way. In many older homes and throughout the different owners, some folks wired receptacles as a "bootleg" ground. The best method to determine if any "bootleg" grounds exist in an older home is to visually inspect if the receptacle has a ground wire terminating on the green grounding screw and splicing into the neutral wire. If the branch conductor wiring is only a 2-wire system and no metal conduit or no bare copper ground and the cube tester shows it is properly grounded, that receptacle was wired as a "bootleg" ground and is not code compliant.
Hope this helps.........If you have any additional questions, let me know and I'll be glad to answer them for you.
Otherwise, don't forget to rate me before you log Off.
The next time you have an electrical question, you can also request for me at: http://www.justanswer.com/home-improvement/expert-your-electrician