Beginner that needs review

I have had some background in brewing cider but that was years ago just to make alcohol. Now years later i have the time, space and money to begin brewing again. I have read Homebrewing for dummies before my first batch and yesterday i have just put my third batch into the primary fermenter. I have had my first batch in bottles for 10 days and have tried it. It is carbonated well but has a very bitter taste and i believe this is from leaving the grains in too long at to high of a temperature. I have my seconed batch in the secondary fementer. What i would like to get out of this post is to help clean up my brewing technique so i wrote down everything in an book i will be using for my brew recipes. Well yesterday September 31 i attempted to make a hoppy pale ale by means of extract brewing.
1.I started off with bottled water and boiled 2.5 gallons to 160 degrees.
2.added 1.25 pounds of 10L for 30 min moving the bag every 10 min or so.
3.In a side pot heated up .5 gallon of the bottled water to 160 and after the 30 minutes was up i poured the .5gallons at 160 over the grains and into the brew pot where my grains were steeping.
4.Brought to a boil and added 7 pounds of pale ale malt extract. The temperature is around 210 now.
5.I started my hop cycle with 1 ounce of chinook hops for 60 min
6. .5 ounce of cascade for 30 min
7. .5 ounce of cascade for 15 min
8. 2 table spoon of irish moss for 10 min
9. .5 ounce of nugget hops for 5 min.

Ok Now i have my wort and used a wort chiller that i made it took about 45 min to cool down but i did not time it. My wort chiller is home made 25 feet copper. This is where i think i went wrong in my brew. When chilling the wort it goes down to around 100 within 15-20 min but does not go down fast at all after this. I added almost a gallon of water at room temperature to help it cool down and i got it to around 83 degrees. Also i want to know if this is wrong to do? Should i wait or is it ok to add the rest of this water at this point? Also when i poured my wort into the primary bucket i left a little less than half a gallon with all the sediment in the brew pot because i am trying to get a clearer beer. Is this ok or am i leaving too many sugars behind? Also with the yeast i keep at room temperature for 2 hours then i poured in a pint of water at room temperature before adding it to the wort. Was this ok? Then i poured the other gallon of water into the primary bucket with my wort. I have been reading that i need to prep the yeast 2 days prior to brewing. I used a liquid yeast White labs California ale yeast WLP001. I think i got enough oxygen into the batch, but today 24 hours later there is no activity. This happened with my last batch but it started on the second day. Any tips and advice would be great. Thanks for reading. Any links or book recomendations would be great. In the future i would like to begin all grain brewing but i want to get extract brewing down first.

sorry my Specific Gravity is 1.043 and 12% sugar and 6% potential alcohol.

Your process sounds mostly fine. Couple things here:

You shouldn't add water to liquid yeast, you should pitch it directly or make a starter before hand. You can find lots of info on here about yeast starters.

With your technique, you can top off like you did; it is fine as long as your water is sanitary. The most important part of cooling is getting it below 140 degrees quickly, which your chiller did fine.

It would help your sanity and your process if you used a hydrometer to take readings before fermentation and during the process. When you say there is no activity, that might not be accurate , and you can only really tell with a hydrometer. Your fermentor/airlock might not be sealed. It can also take 72 hours (or more) to show signs of fermentation, which many other posters on here will remind you.

Your steps look pretty solid.

I ditto picobrew in saying that adding the WL001 to a pint of water is a bit strange, but probably not harmful. One vial (abeit big vial) of White Labs yeast is a bit on the small side, so I'm not surprised your fermentation is a bit slow.... it'll take off as soon as the yeasts have enough time to grow, multiply, and eat up all the O2....

As far as steeping your grains: try not to steep your specialty grain in water (or rinse water) over 170 Deg F. I personally think your beer is still young at 10 days in the bottle. Let it set for another week or two. Your bitter tastes are probably coming from "young" beer rather than from "hot" steeping the grains.

RDAHAHB !