Questions about Pathology Report

In December 2010 my PSA was 5.55; a subsequent biopsy revealed 10 of 12 positive cores with a Gleason of 8. Since I was 62 years old and since the bone scans etc. were negative I opted for the robotic prostatectomy in March 2011.

The first post-op PSA, July, 2011, was 0.0 (the urologist and I were both quite pleased); in March, 2012 the reading was 0.12 (and he told me not to worry because that could be attributed to lab error and in any case was insignificant); but, in October 2012 it was 0.22 (and he advised to "observe for now" and retest in 6 months.)

I recently obtained a copy of the surgical pathology report about which I have some questions:
1. The prostate weighed 28 grams and its measurements were 4.8 x 4.0 x 3.0 cm.
What is the significance of the weight and size?
2. "Invasive tumor involves approximately 50% of prostate. Tumor is multifocal, bilateral, and present from apex to base. It involves up to 2.8 cm of confluent prostate tissue and involves 10 of 19 tissue blocks of prostate.”
Does that indicate an aggressive form of cancer?
3. “Margins involved by invasive carcinoma, multifocal, right and left posterior lobe. Tumor also comes multifocally within 0.5 mm of the margin.”
Does “margins involved” mean the same as “positive margins” in other words, that some cancer may have been left behind? Or is that qualified by the second sentence which seems to say that the tumor comes “within 0.5 mm of the margin.”
4. Lymph Vascular Invasion and Perineural Invasion was said to be “Present, multifocal.” And the report also stated, “Tumor is focally present in periprostatic adipose tissue at base of prostate and is extensively present within lymphatic and vascular channels in extraprostatic adipose tissue.”
What’s the difference between “focally present” and “extensively present” and do these observations also indicate an aggressive cancer which may still remain somewhere in my body?
5. The cancer was staged as pT3a, pN0 with the notation that 8 lymph nodes were examined and "no regional lymph node metastasis was observed." Is there a standard number of lymph nodes that are examined before the pN0 stage is "awarded"?
And with regard to the seminal vesicles it was noted, “Seminal vesical tissue is mostly separated from the prostate secondary to surgical excision. Even so, the entire base of the prostate in area of seminal vesicles is submitted without definite involvement of a scant amount of seminal vesicle tissue present... Also sampling of separate fragments of seminal vesicle tissue ... are negative for malignancy.”
In another part of the report there was a statement: “Seminal Vesicle Invasion: Not identified.”
What’s the significance, if any, of the terms “Not identified” as opposed to “negative for malignancy”?
As noted above, while the post-op PSA's remain relatively low, the last two tests showed an increase in the PSA; given the pathology report, should I be concerned? In another thread, I was advised to request PSA testing sooner rather than later and to research options. I've done a lot of research but received a lot of contradictory information and every time I start the research I become anxious. Before I ask the urologist for another appointment, a sooner PSA, and a discussion of options, I'd like to figure out this pathology report so I can communicate my concerns. Any help would be greatly appreciated. Also, I still remain severely incontinent since the operation in March 2011 so that may also limit future treatment options, right?