why weechat, why not irssi?
for example: channel list bar (buffers.pl) and native nicklist, dynamic buffers, kept in order (/layout apply), interactive search, vertical splits, easily and widely customizable (can change everything with /set), dynamic filters, scrollable bars, great development

how can i change the target server?
ctrl+x (/input switch_active_buffer)

how can i make weechat remember my channels/layout?
/help server (eg. /server add efnet irc.efnet.org), /set *autojoin*, /set *autoconnect*, /help layout

how can i get that channel list bar on the left side?
use script buffers.pl

how can i make the buffers bar smaller?
/set weechat.bar.buffers.size_max

how can i get noticed of highlights
use script beep.pl (or launcher.pl)

how can i change the colors of topic and status bar?
/set *title*, /set *status*

how can i filter voices?
/filter add hidevoices * irc_mode \(\+\|\-\)v

how can i filter joins/parts/quits?
/set irc.look.smart_filter on & /filter add irc_smart * irc_smart_filter * or /filter add joinpartfilt * irc_join,irc_part,irc_quit * (/help filter)

how can i put nicks more left?
/set weechat.look.prefix_align_max

how can i disable nick aligning?
/set weechat.look.prefix_align none

how can i search from buffer (like /lastlog in irssi)?
interactive search: /input search_text (ctrl+r by default)

are there themes for weechat?
theme script is under dev