Summary:
The desirable גירסא would be ערבי פסחים; however ערב פסחים can be referring to the many קרבנות פסח that were offered, or to either פסח ראשון and פסח שני.
One should not eat close to Minchoh - סמוך למנחה לא יאכל
Summary:
In one meal a person can pace himself not to overeat (but, not necessarily not to overdrink) in the same meal, however one may overeat if he thinks that by the next meal he will have an appetite. Making קידוש and eating מצה may be considered as two separate meals.
Summary:
The משנה mentions עד שתחשך either because we cannot eat עד שתחשך on ע"פ, or because one might have thought that we can eat before עד שתחשך, since the פסח was already brought.
