Karpas - Issues and Sources

Poskim Debate the following issues re: Karpas

1. Washing Before
Issue: with a B'rachah or without?

2. Eating Kapras
Issue: K'zayit or Less?

3. When eating a K'zayit of Karpas -
Issue: Making a B'rachah Acharonah [BNR] or not?

Which in turn relates to having in mind the Marror when reciting Borei P'ree Ho'adamah

Preliminary Sources:

Rambam M"T Hil. Hameitz uMatzah 8:1

Rambam La'am there quoting the Ga'onim, the Haghaot Maimoniyyot and the Maggid Mishneh.

SA O"Ch 473:6

B'er Hagolah there "qof" quoting Rosh et al.

Ba'er Hetev 18 quoting the Tur M"B 53

Bei'ur Halachah D"H Pachot mikkazayit

There the Rashbatz is quoted that The Rambam requires a K'zayit Karpas in order to trigger a b'rachah of al N'tilat Yadayim.

Similarly the Shaar haTziyyun 473:70 quoting the GRA - who does make a b'rachah Al N'tilat Yadyaim - opines there that the b'rachah on washing would be "davka im ocheil k'zayit"

Mashma, if one washes sans a b'rachah, it's arguably better to NOT eat a k'zayit. 

Best Regards,
RW